JANNI AND ROHAN carefully inspect our gear and spearguns. After they finish, my father’s helper staff hands out spear darts tipped with powerful explosive charges, or “boomers,” as everyone at Safety Harbor calls them.

:In case shredders or large sharks attack us, each of you will be issued one of these today,: Janni tells us soberly, nodding toward the boomers. :I know you’ve been practicing with mock-ups, so remember to be careful as you carry these. If you trigger a boomer by accident, it could blow off your head or your hand.:

I watch as Janni slips her own boomer cautiously back into her quiver. I really hope we don’t run into shredders today. Those mutates sound so dangerous, I wonder if the boomers could truly help against them.

Vival, Dav, and my father wish us good luck, and then Janni leads us through the bubble wall. After we cross it, Mariah and her family swim excited circles around us. Four dolphins from the Safety Harbor pod join us as well. Soon we settle into our travel formation with Janni swimming point, Seth bringing up the rear, and our dolphins swimming protectively around us.

Although we’re constantly on the lookout for danger, I can’t help smiling when we come across a group of playful sea lions diving, flipping, and twisting through a nearby kelp bed. A curious pod of black-and-white Dall’s porpoises, which look like small killer whales, keep pace with us for a time, and once we even hear a pod of real orcas squealing and calling to one another in the distance.

As we swim, Janni explains Sea Ranger procedures for dealing with various threats, from sharks to Marine Guard vessels. Clearly she sees this time as a chance to further our training. She even talks to us about Sea Ranger protocols for hunting. I’d be more irritated with her, but I’m starting to understand that Janni wants to keep us safe, and her lectures do help to keep my mind off Bria and Robry, and where we’re going.

We’re three hours out from Safety Harbor and making good time when the dolphins start whistling and clicking in alarm.

:What is it?: I ask Sokya. She’s scouting the waters to the south of us.

:there are many shark people coming.:

A shiver races down my backbone. :Can you send me a visual?:

Halia, who is with Sokya and can’t communicate in human words, sends me a vivid picture instead. I try not to panic as I absorb her image of several strange shark mutates cutting swiftly through the sea. They look like strong teen guys with elongated shark faces and sharp teeth.

:I think the dolphins just spotted several shredders,: I tell Janni quickly. :And they’re headed right for us!:

Janni doesn’t hesitate. :Signal your dolphins that you need a tow, and load your boomers. We have to be able to react quickly. Stay in tight formation as we keep heading south.:

:We’re still going on? Shouldn’t we try to hide from these things?: Lena asks exactly what I’m thinking.

:Our job is to get to Atlantea as quickly as possible,: Janni snaps. :Last time we saw these shredders, we kept calm and pretty much ignored them, and after they checked us out, they left us alone.:

Tobin and I exchange looks of disbelief. Right now we’re in open water with only sandy bottom beneath us.

:But, Janni,: I blurt, :we just passed an underwater canyon that could give us some protection if these mutates do decide to attack us.:

:I’m the leader of this mission, and I say we stand a better chance if we keep going,: Janni retorts. :Your job is to follow my orders, whether or not you’re the doc’s daughter.:

Is that what’s been bothering her? I don’t have time to deal with her issues now. Instead, I call Sokya to tow me, and I tell her that the rest need tows, too.

:Mariah, we’re going to try to slip past those shark mutates, but no matter what happens, you and Tisi hang back.: Mariah’s like a mother to me, and her language abilities are so valuable, I never risk her life in a fight if I can avoid it.

:be careful. they feel very wrong to us,: she warns me.

:We will be.: I hope I can keep that promise.

Our dolphins quickly find their human partners while three from the Safety Harbor pod come to tow Seth, Janni, and Rohan. I take hold of Sokya’s dorsal. She surges forward, her powerful tail propelling us both through the sea. My heart is thudding against my ribs as our brave dolphins pull us toward the approaching shredders.

:There they are!: Janni says, pointing to the southeast. :I’m going to lead us around them. Have your spearguns ready just in case the shredders do attack, and Penn, get ready to turn on your jammer if we need it.:

At first all I can see are six dark shapes kicking swiftly through the water. As they draw closer, I shudder. Their bodies appear human, but their faces are impossibly long and pointed. They swim with their mouths partly open, the way sharks do. A big school of Pacific cod darts away from them in a silver flash.

When the shredders get closer, I see they have at least two rows of sharp, pointed teeth in their lower jaws. Their eyes are a flat, dark slate, with little sign of feeling, like bull sharks and great whites.

I feel Sokya’s fear rising, just like my own. I give her a quick rub, then grip my speargun tighter and get ready to fire.

But the shredders don’t attack us. Instead, they swim right past our team. At first I think they are going to ignore us completely, and then they turn and start circling around our group.

:Should we turn on the jammers now?: Penn asks Janni tightly, his hand hovering over the small square device clipped to his utility belt.

:Not unless they charge us. This is like what happened last time. They just watched us and we watched them,: Janni says, her mental tone cool. She might seem calm, but these mutates have me completely freaked. :They didn’t attack us that day, but they did tear apart one of our dolphins when it got curious and swam too close.:

:You’ve told the dolphins to stay away from them?: Seth asks me anxiously.

:Oh yeah,: I reply. :My dolphins want nothing to do with these things.: It’s eerie to watch the shredders swim in perfect unison, just the way schools of small fish do.

:Hey, Nere, check that out.: Kalli points to a shiny shape in the distance. There’s a small triangular-shaped sub hovering to the south of us.

:That’s probably the same sub they used to snatch Robry and Bria,: Tobin says, his face flushing.

:I bet someone in that sub is controlling them.: Penn jerks his head at the shredders. :Do you want to try and get a read on whoever’s driving that thing?: he asks me.

:Good idea.: I close my eyes and extend my senses, but I’m overwhelmed by an intense, gnawing hunger close by. I open my eyes and stare at the shredders circling us.

:Those shredders are starving,: I tell the others as goose bumps chill my skin. :It’s like all they can feel is hunger. They desperately want to eat us, but something’s stopping them.:

:Or someone,: Penn says with another glance at the sub.

I close my eyes again and push past the waves of hunger coming from the shredders. Farther away I touch another mind, one that’s dark and angry. There’s a man in the sub, and he’s completely focused on the shredders. He feels possessive toward them and eager to see how they perform.

Then I sense a different mind, one I’ve encountered before.

:I think Wasp is with that sub,: I warn everyone.

Seconds later, the shredders halt their circling and charge straight at us.

:Penn, hit your jammer!: Janni cries, but she doesn’t have time to press the button on her own. She’s too busy shooting the lead shredder in the head. Her boomer explodes with an orange flash, and the shredder veers off, its head partly blown away. Then a second shredder is on her. She tries to hold it off with her empty speargun. The creature reaches out and slashes her shoulder with its sharp, curved talons.

I lunge forward and shoot the shredder in the face. My boomer blows a hole between its eyes, but it keeps coming, trying to rip us apart. Desperately I shove it away with my empty speargun. The shredder claws my forearm, but the mutate’s strength is finally fading. The creature falls away from us, twitching and seizing. A third one streaks downward and begins to tear at it.

Our entire group fights the remaining shredders now. The dolphins help where they can, ramming the shredders with their hard beaks. Intently focused, Thom fires at a mutate charging Ree. Kalli shoots at a shredder trying to get at Lena. Kalli’s boomer tears a hole in its side. The wounded creature breaks off its attack and dives to feed on the crippled shredders below us.

I see one of the monsters has latched on to Seth’s thigh, and I reload my speargun with a regular dart as fast as I can. The shredder shakes Seth the way a great white shakes a seal. His loyal dolphins keep ramming the shredder’s ribs. I can’t get a clean shot—the dolphins are in the way! At last the mutate breaks off the attack. Penn finishes it with a shot through its gills. Twisting and lashing around in a dark cloud of its own blood, the shredder sinks into the midnight depths beneath us.

Now there are only two shredders left swimming. Both are wounded, but they still devour the dying ones. After Thom and Ree kill them by firing spear darts through their heads, they drift down beyond the limits of our vision toward the black floor of the strait.

I glance at the sub, gulping when I spot a second group of eight shredders passing it and closing on us fast. We’ll never be able to fight off this second wave! I reach out with my mind, scanning them for any weakness. Once again, I’m overwhelmed by their searing hunger. A desperate idea comes to me.

:Sokya, take Nika and drive that school of cod to the east of us into the shredders. The fish might distract them.:

:we go,: Sokya says, and our two fastest dolphins streak away.

:Eight more shredders heading our way!: I warn our group. :Mariah, keep an eye out for real sharks, too.:

I glance toward Janni for orders. Clearly she’s struggling to stay conscious. Tobin’s already working on her shoulder and Rohan is bandaging a nasty bite wound in Seth’s thigh.

:You take command,: Janni says faintly. :I’m useless now.:

:’Kay,: I say, fighting panic. We’re out of boomers, we don’t have time to race back to that canyon, and the jammers appear to be worthless.

:Let’s circle up around Janni and Seth,: I tell the others, :and reload our spearguns.:

My blood thunders in my ears as I watch the shredders drive through the sea. They swim impossibly quickly, their legs kicking with machinelike efficiency. Where’s Sokya?

The lead shredder is so close now that I can see its dead gray eyes. Trying to keep my trembling hands steady, I raise my speargun and aim for its head. I can’t afford to miss. But even if I manage to kill this one, seven more will be on us in seconds.

Taking a deep breath, I squeeze the trigger. The speargun recoils in my hands as my dart pierces the lead shredder’s eye. The creature stops, but the others keep charging!

I raise my empty speargun, hoping to fend off the next shredder rushing toward me. It’s so close that I can see a third row of jagged teeth in its lower jaw. Suddenly, Densil rams it so hard, he knocks the mutate away from me. Before the creature can twist about to attack either of us, a school of silver cod darts through the shredders, desperate to escape the dolphins chasing them. The starving mutates break their perfect formation. They chase the cod in every direction, frantically gobbling them down.

Ree coolly picks off a shredder. I reload and wait for my chance. A frenzied shredder flashes past me, gulping one cod as it chases another. I send a spear dart through the gills at its neck.

Another shredder veers toward us, intent on devouring three fish that race ahead of it. Thom’s beside me with his speargun loaded. :This guy’s yours,: I say.

Thom fires, and his dart buries itself in the shredder’s belly. Two more shredders stop charging us to tear apart the one Thom wounded. Tobin takes out the first, and Lena shoots the second.

The last two shredders start back toward the sub as if someone called them off us. But seconds later, they break formation and dive down to feed on their dying companions. Kalli, Penn, and Thom finish them off.

I feel the fury of the man inside the sub. Cold dread washes over me as the sub speeds toward us. What if it’s armed with torpedoes?

But the sub veers away and heads south, and I release a deep breath. Our dolphins come to find their human partners. I think they’re as shaken as we are. Mariah, Tisi, Densil, and Sokya crowd around me, and I rub their flukes.

:Densil, you just saved my life, and Sokya, you were wonderful. You and Nika saved everyone.:

:I am glad you killed those things,: Sokya says as she tilts to stare at the shredders sinking into the shadowy depths. :they are even worse than the big sharks.: For once, Sokya’s mental tone is subdued.

:We have to hand over Seth and Janni to medics from Safety Harbor as quickly as possible,: Tobin tells me. :They’re both too badly injured to continue on to Atlantea.:

:Is anyone else hurt?:

:Just you.: He nods toward my forearm. The cuts burn like crazy, but I’m relieved to see they’re shallow. Lena comes over and helps me wrap a pressure bandage around them.

:Mariah, keep an eye out for that sub, and for more shredders and sharks.:

Shortly, we’re racing back to meet a medical team from Safety Harbor. We swim in a close formation, keeping an eye out for trouble. I don’t want to think about the precious travel time we’re losing.

:Just how many of those shredder monsters do you guess Kuron has?: Lena asks me the question I think we’re all worrying about right now.

:I don’t know. If he has lots of them guarding Atlantea, it’s going to be a whole lot harder getting in there,: I admit grimly.

:Maybe we can still sneak into the fortress, but how are we going to get away if he can send a hundred more shredders after us?: Kalli asks. :Those jammers were useless.:

:I’ve been thinking about the jammers, and I don’t think they are useless,: Penn speaks up. :Janni never turned hers on, and once mine was on, the shredders stayed away from me. Nere said the shredders were starving, and they acted like it. I think we can count on their drive to feed to override everything else.:

:They did do more damage to one another than we did to them,: Tobin points out. :The moment one of them was wounded, the others turned on it, and whoever was in that sub couldn’t stop them.:

:So if we have the jammers and we wound enough shredders to get them to turn on one another, and we have help from the Sea Rangers, maybe we can manage to get away after we find the c-plankton,: Thom says.

:If that fortress is full of those shredders, we really have to get our niños away from there, and we still have to try to steal that c-plankton,: Ree tells us. :I vote we go on.:

:I agree we should keep going, too,: I say, and Tobin sends me a grateful look.

But will the rest want to come? I wouldn’t blame them for turning back. My throat goes tight as one after the other, each of my old friends from the southern sector votes to continue with our mission. Rohan does as well, and he even volunteers to take Janni’s place on the team that stays at Atlantea to search for the c-plankton.

Soon we meet up with the medical team from Safety Harbor. I stay near Janni as the medics transfer her carefully into a stretcher strapped on the back of a big tow. Her eyes flutter open and her gaze meets mine. :You told your dolphins to distract the shredders with the fish, didn’t you?:

I nod.

:Quick thinking. Sorry I’ve been so snarky. Guess I didn’t like the way people kept talking about your long trip here and your being Doc’s daughter. I’d go on a mission with you any day.: She sends me a weak smile, and then the medics close in around her.

:Is she going to be okay?: I ask Rohan.

:Yeah, I think both she and Seth are going to make it,: he reassures me. After passing us a new round of boomers, the medics speed away on their tows. As I watch them disappear into the green sea, a part of me really wishes I were going back to Safety Harbor, too.