Once the fire was out and they were well clear of the eels, Gene brought the boat to a halt so they could assess the damage.

Blackened splits of burned wood braided the deck, a charred map of where the current had been strongest. Thankfully, the fire had not spread far; a smouldering hole in the deck could be easily patched and the plastic tent was only a little melted. A handful of books and papers had burned and Anil was busy salvaging what he could while Zoey and Gene checked over the engine.

“We should probably swap out the spark plugs,” suggested Gene.

Zoey nodded appraisingly. “I suggest a full inspection of the rear gasket cylinder head and a complete audit of driver housing clamp screws.”

She peeked over a shoulder to check if Bridget was listening. The other girl was too busy scrubbing her chipped fingernails with a coarse brush.

“I think there’s eel gunk in my cuticles,” she whined.

“You were wearin’ gloves,” Grandpa pointed out.

“Out, gross spot! Out, I say!”

Alex had been excused from the clean-up on account of being slightly electrocuted. Every centimetre of his skin still tingled from the shock and his fingertips were numb. If he stood up, he wasn’t sure his legs would hold him.

Grandpa slathered cold, sticky burn salve onto Alex’s hand.

“Is this enough?” he called to Anil, undoubtedly the member of the crew with the most medical knowledge.

“More,” Anil called back absent-mindedly, studying a singed leaf of paper.

Grandpa squeezed the tube as hard as he could, splattering salve all the way up to Alex’s elbow.

“That seems like too much,” Alex protested.

“Doctor’s son’s orders.”

Next, Grandpa wound a long length of bandage around the wounded hand, swaddling it tight, salve squeezing out between the gaps. Kraken pawed at Alex’s hand tenderly and pressed close to his cheek as if she would never leave him again.

“How many times a day do we need to change this bandage?” Grandpa called.

“Hmm?” Anil wiped soot from the cover of a book. “Oh, twenty?”

Grandpa frowned. “That seems a lot.”

Night fell rapidly at sea, the horizon seeming to close around the boat each time Alex glanced away. Usually there would be other lights on the water, distant ships and lonely outposts. Tonight he saw none. The darkness promised to be absolute, as if they alone dared sail through the night. Maybe the recent storms and rumours of a vengeful dragon had kept everybody else on dry land.

Alex searched behind the boat, wondering if he might still be able to catch a glimpse of Haven Bay as its lights came on. But they had travelled too far from home.

“So do you have electrical powers now too?” Zoey asked, once the engine had been serviced and they were back on the move. She hovered a hand close to his skin as if expecting a shock.

“No, I just have pins and needles in my knees.”

Zoey sat beside him on the deck, back pressed against the upright of the rail. “I’ve been thinking.”

“Uh oh.”

She lightly punched his arm, snatching her hand away at the snap of a static spark. “The infected animals back home could be aggressive, but it was usually only if they were provoked or people got too close. They never attacked for no reason, and never as a group like those eels.”

“We must be getting closer to the dragon.” Alex straightened a little. “They were trying to stop us before we could interfere. But how can they plan an attack like that?”

“There’d have to be a way for the parasites to communicate with each other between hosts.”

Alex remembered how his connection to the infected animals – to the dragon – had felt blocked. There had been a presence there that he hadn’t been able to identify. Now he wondered…

“Do we still have that eel?”

After using it to jump-start the engine, the eel had been dropped into Kraken’s tank so that Zoey could study it. Alex, still slightly unsteady on his feet, approached it. On his shoulder, Kraken crossed her arms sulkily at having lost her tank.

Drops of water had run down the outside of the glass. Alex reached for them with his unbandaged hand. The eel crackled with electricity but the charge stayed safely contained within the tank.

The moment Alex touched the water, he felt the stifled thread between him and the creature. He closed his eyes and pressed at the blockage with his magic, testing it for any sign of weakness. It held fast, his power waning when it came into contact.

But this time Alex was aware of another presence moving along the thread, like a louder voice shouting down the line so he or the dragon couldn’t be heard.

“The parasites aren’t just blocking the ocean threads.” Alex opened his eyes. “They’re using them to communicate between infected hosts.”

“Which means you can’t use them at all!” Zoey shook her head. “That’s…really annoying.”

Alex crouched to bring his gaze level with the eel. Its thick, flexible body shimmied from side to side to hold it in place.

“We’re going to beat you,” he told the parasites watching from behind the eel’s eyes. “The dragon is still fighting you, so we’ll fight with everything we have too.”

“Because when the situation looks impossible, that’s when you have to fight your hardest,” Zoey said.

Together, with Kraken cheering them on, they tipped the electric eel overboard. It wriggled away as soon as it hit the water.

Alex looked around the boat. Lamps had been lit to wash the deck in orange light. At the helm, Bridget and Gene talked in hushed voices, while Grandpa fussed over the cannon with an oily rag. The otters had teamed up with Chonkers to steal food from a cooler.

Beside the tank, Anil seemed to have finished gathering up the damaged records and was trying to lay them out in order.

“Did you lose anything important?” Alex asked.

“The problem is that we don’t know exactly what is important.” Anil sighed. “Even a couple of burned-up lines could be the difference between finding the cure tonight or in a week.”

Alex was surprised to feel a flash of annoyance. Obviously the archive was important, but during the eel attack Anil’s decision to protect it had almost lost their only chance of escape. It made Alex worry how much influence Erasmus Argosy might be developing over his friend.

Behind the crate, Argosy sat on a camping chair. There was a book open in his lap, but Alex was sure the old man was listening to their conversation.

A flap of wings brushed the tent roof as Pinch descended from the dark sky. The seagull held a lightly scorched fragment of paper in its beak.

“Great, you’ve brought me more litter.” Anil took the paper, ready to scrunch it into a ball. Then he spotted something on the page and his eyes widened. “That’s how I can find the right year.”

“What do you mean?” Alex asked.

Anil grabbed a book and riffled through its pages, before jabbing his finger at a long list of barely legible handwriting.

“There was an assistant naturalist who kept a journal during an expedition around the Outer Hebrides. He refers to an article in the winter edition of the Cornish Coastal Review next to an excellent pastie recipe.” Anil jumped up onto a stool to reach inside the crate, snatching up a stack of dog-eared magazines. “I know I’ve seen that somewhere.”

“The pastie recipe?” asked Zoey, licking her lips.

“No, the article!”

Argosy got to his feet and came to watch Anil flip through the journals, dismissing each one in seconds when he didn’t find what he needed. Alex wondered if they should help, but it seemed like they would only get in his way.

“Here!” Anil crowed, pointing triumphantly to a page dedicated mostly to hand-drawn depictions of sea snails. “And this article refers to a biologist who specialized in marine insects. But there’s no name! If I had that, I could dig out their work and see if they knew about the parasites. Maybe if I find passenger lists for ferries in that area…”

Alex had seen Anil attempt to master countless hobbies over the last few months, but he had never seen him like this.

“It’s like watching a composer put together a symphony,” he said.

Zoey nodded. “Or a conspiracy theorist posting on an internet forum.”

“I’m on the trail of the cure. This was the breakthrough I needed!” Anil hugged Pinch, squashing the seagull against his chest. “If there are no more distractions, I should be able to—”

Grandpa’s voice rang along the deck from the stern of the boat. “Flotsam in the water! You better come and look at this!”

Anil sighed. “I knew I shouldn’t have said it out loud.”

They hurried to reach Grandpa at the back of the boat. Night had settled heavily on the water. Beyond the rail was total darkness, any trace of the world erased. Grandpa peered through an eyeglass into the inky black. Everybody peeled their eyes in the same direction.

“You can’t possibly see anything,” said Argosy.

“I ruddy well can!” Grandpa pointed. “Look.”

Alex strained his eyes. There was nothing there. The absolute night almost made it impossible to imagine anything could be there.

Until he saw it. Faint and blinking in the distance.

A light bobbing on the water.