Rathbone and Rebecka stood motionless, gazing at the rapids below the Hoover Dam. They were sure that Dr. Jack Tanner and Aiden were dead. They knew what the doctor’s loss meant to them and to the world. A cure had been within their grasp, and now it was gone.

Rathbone’s men continued to celebrate, but he ignored them as he replayed the scenes of the battle in his mind. A plane passing overhead broke his concentration, and he looked skyward. The pilot stuck his arm out of the small aircraft to give Rebecka a thumbs-up before turning north.

Salvatore was slumped against the small concrete wall that ran along the ledge of the dam. His eyes were glazed.

“What’s done is done,” Rathbone told him, but his voice was cold. He blamed Salvatore for the deaths of Jack Tanner and Aiden, and Salvatore accepted the blame.

“I’m going to send scouts down to the rapids,” Rebecka said. “We’ll walk both sides a few miles down just in case someone survived.”

Rathbone nodded. He wasn’t optimistic, but he’d give Rebecka an hour to search. “Take your men down to the river. I’ll take my people and track Pippa and Abby. Catch up when you can. We’ll get those girls back. And we’ll be prepared for those feral bastards this time.”

Salvatore jumped to his feet. “We have to find them soon.”

“Why is that?” Rathbone asked.

“Because they’ll kill each other if we don’t reach them first.”

Pippa raced up and down the hills and valleys of the brown, rocky terrain, determined to reach her sister before Abby lost herself completely. She’d been running for hours, and the sun was nearing the western horizon. Traveling alone had allowed her time to squelch her anger. The ghost of Keenan and the spirit of her mother had reasoned with her, begged her to control her rage, to master the power of her rabid state, told her it was the only way to save herself and her sister.

Now she understood. As she blazed across the dry earth and felt the power surging inside her, she realized that the rabid state would always exist, but now it was under her control. The thought both excited and frightened her. The beast within had nearly wiped out an entire species of mutated reptiles only weeks earlier, a fate, she now knew, they didn’t deserve. The memories sickened her, and the thought that she once had a demented compulsion to kill Abby, Jack, and Salvatore was almost too much to bear.

She dug a grave in her mind and buried her rabid memories. But she could never bury the memory of Aiden. He had willingly given his life to try to save Jack, and she would never see him again.

Rathbone flew across the dusty terrain at top speed. A young soldier stood straddling the back seat, his eyes continuously scanning left and right, his hands on the mounted automatic. The soldier had already picked off several ferals that had fallen behind their pack, and Rathbone heard a quick burst and felt the Jeep shake as another one went down. Somewhere in the back of his mind he thought the creature looked like a werecat, a hyena, in fact.

Salvatore sat in the passenger seat next to Rathbone. He was grief-stricken at his failures yet determined to find Pippa and Abby. He’d fallen in love and found a family, both supposedly impossible for a hyena. Hyenas were cruel and cynical, and Salvatore had been treated cruelly. His alpha leader said it was to toughen him up, to teach him to fend for himself and never desert the pack.

He hadn’t seen his pack for weeks, not since before the hospital, except for the one that the young sharpshooter in the back of the Jeep had shot an hour earlier. He wasn’t sure if it was one of his own, but he prayed it wasn’t, because that would mean they were close. He almost wished his pack had all been killed, but he knew that a pack of several hundred hyenas could kill ten times as many ferals. If anyone from his pack was alive, they’d be tracking their planted spy, and he knew he’d eventually have to deal with them. It wouldn’t be easy, but he was in love, and he knew he’d have to shake his pack if they appeared. If they made it to the werecat safehold, he knew what would happen.

Rebecka was about to call off the search when a werecat traveling at lightning speed on all fours bounded toward her from downriver.

“I’ve found the scent of the reptile,” he said.

“Keep searching,” Rebecka shouted to her soldiers.

The scent grew stronger and eventually led the searchers to an inlet. They explored it and came to the mouth of a cave. Rebecka was about to ask for volunteers to search the cave when she felt a chill in the air. She saw shadows flickering in the far corners of her peripheral vision and felt as if ghosts were watching her. Dozens of humans emerged from the shadows and pockets carved into the cliff. Her werecats morphed, and her men aimed their weapons. “Ferals,” someone whispered.

Rebecka shook her head. “Hold your fire,” she commanded. “But be ready.”

The humanoid creatures walked toward them. Their skin was gray, their faces striped in black and white. Their huge round eyes seemed lifeless. Rebecka recalled fairy tales of zombies from her youth. Her men surrounded her, waiting for the order to shoot.

“Rebecka,” a voice called from the cave. The voice was Jack’s.

Rebecka spun around to face the cave and saw Aiden emerge, followed by Jack. The doctor looked as if he’d been drained of life. His skin was pale, and his eyes were pure black. Three nightmare creatures followed close behind. Huge bat-like wings hugged their bodies, and, except for their dark, piercing eyes, their faces were blank and featureless.

Rebecka swallowed and extended a hand. “Jack? Aiden? Are you all right?”

“We’re okay,” Aiden said. “Everyone can stand down.” He gestured toward the winged beings. “They’re not ferals. They saved Jack’s life. They’ve given us another chance to end the feral infestation. We need to get Abby back and continue on.”

“Pippa went after Abby,” Rebecka said. “Rathbone and Salvatore and Rathbone’s men are following her. We stayed behind to look for you two, but I didn’t expect to find you alive.”

“No time to explain. We have to get going. They can’t defeat the ferals without us!”

Rebecka motioned to her men to leave the gully, but she kept a wary eye on the creatures. “If we hurry, we might catch up to Rathbone before it’s completely dark.”

Jack walked up to Rebecka and took her hands. His touch was cold, and his pale skin and black eyes nearly unnerved her. She wondered if he had always been a hybrid, like Aiden, or if the three creatures were responsible for his transformation. “We’re not going with you,” he told her.

Aiden stared at him. “What do you mean we’re not going with them?”

“Things have changed,” Jack said. “When you chose to bring me back to life, you knew there would be consequences. The nocturnals’ bites give me not only a part of their life but also a part of their memories. I am nocturnal now, and I’ve seen the devastation we’ve endured since the Final Cataclysm.”

The doctor went silent for a moment, searching for his next words. “You know, I envied Pippa, Abby, Salvatore, and even you, Aiden, for your mixed blood. Now I’m not so sure. All I know is that we’ll have to travel at night so that we can see our way. My eyes are too sensitive to light now. I’ll never find my way. Rebecka, please take your men and go. We’ll catch up as soon as night comes. I promise I’ll find you.”

Rebecka was stunned. “I thought the nocturnals were just a myth.”

“They’re real,” Jack said.

“But, Jack, if we wait until nightfall, they’ll be too far ahead of us,” Aiden said. “We’ll never catch up. How will we reach them on foot?”

The lesser nocturnals, the ones the three beings referred to as their children, raised their arms, revealing large flaps of skin that extended from their lower ribcage to their armpits. The flaps formed what looked like half a kite on each side of their bodies.

Aiden remembered what the three creatures had called the “children”—sugar gliders. The three beings now projected their thoughts into the minds of the humans. Our children possess the false wings of marsupials. Though not fully hybrids like ourselves or the doctor, they have wings to carry them on the wind.

Rebecka looked at Jack. The beings had just said—or sent a thought into her mind—that Jack was a hybrid. Jack removed his shirt to reveal his own metamorphosis. Save for his grayish skin and black eyes, he looked almost normal, but now Rebecka saw that wings of flesh, like those of a bat, extended from his body.

“The nocturnals and I will glide on the winds to reach you,” Jack said.

“These creatures are coming with you?” Rebecka had heard too many ghost stories about nocturnals to trust them. “I don’t know if that’s wise. I don’t know if Rathbone will approve.”

We are sending them to protect you, the three beings projected. We three will stay here and await their return. It is our home, and our children’s home. Our children will follow the doctor, see him safely to the mountains, and return to us when it’s done. They go.

“They go,” Jack Tanner repeated.

Rebecka reluctantly nodded. “I trust you, Jack.” She gave orders to her troops, and they quickly departed.

“How will I keep up on foot with winged humans?” Aiden asked Jack after Rebecka and her men left.

“You’re a hybrid. Dig deep and run like a leopard, swim like a reptile. You’ll find a way.”

Pippa had followed the ferals’ trail for several hours, but the tracks had dwindled and finally disappeared. She recalled her brief time as a mud monster and wondered if she were being lured into a trap. She still smelled the stench of ferals in the night air, could still distinguish her sister’s blood. The smell was heavy, and she worried that they might fall on her at any moment. They were close, and she feared that Abby might have been injured during the fight on the dam.

She dropped to a crouch and inched forward slowly across the flat, open land. She peered through the darkness at what might have been a stretch of highway. The moonlight glinted off a shiny piece of metal a hundred yards ahead. She crept toward it. Her heart fell when she realized it was the cross that Mother Frances had given to Abby, identical to the one Pippa wore around her own neck. She had all but forgotten about the keepsakes during their cross-country trek.

If Abby had begun to return to normal, the ferals would have torn her apart. The cross might be all that was left of her. As Pippa reached for the necklace, she saw a puddle of blood near the cross, staining one of its edges. She felt motion as the ground gave way and dropped her into a trap.

She had fallen into a sinkhole like the one that had swallowed their armored vehicle. Guttural voices filled the air above the hole. Dozens of ferals appeared at the top of the pit, glaring down at her. The ferals were communicating among themselves, though the noises were limited to grunts and squeals. Her mind reeled. It seemed impossible that these animals were smart enough to set a trap, yet here she was.

“I killed your leader, you savages,” she screamed, sure they couldn’t understand her. Hatred filled their eyes as she continued to taunt them. “You’re all next. Jump down here with me, and I’ll tear you apart one by one. Bring me your new leader, and I’ll start with him!”

The ferals moved apart, creating an opening. They bowed their head as if in reverence.

Abby appeared at the edge of the pit.

“Abby?” Pippa called. “Abby, are you okay?”

Pippa noticed blood dripping from her sister’s wrist from two bite marks. “They bit you? They used your blood to lure me?”

“You requested their leader,” Abby said in a menacing, disconnected voice. “Here I am.”

Abby smiled and jumped into the pit to kill her sister.