Sky, sitting behind Alex on Simber’s back, gripped Alex’s arms in fear and worry. But Alex didn’t feel anything except pain in his stomach at the thought of his friends being sucked down deep under tons of seawater, trapped inside a hidden, hostile, and dangerous world.

Sky and Alex scanned the waves. “Should we go down?” Sky asked. “We should go down. Shouldn’t we?” Her fingers drummed Simber’s back, and she couldn’t sit still.

“No,” Alex said. “I want to as much as you, but it won’t do any good right now. Ms. Octavia will be back soon.” He shivered with nervous energy. “I don’t think they made it out. That outer door opens so slowly. . . .” He trailed off, unable to think straight enough to finish the thought.

They flew in silence as the minutes ticked by.

There was nothing else they could do but hover and wait. Eventually Simber asked, “What did you yell earlierrr, Alex? Just beforrre the island sank?”

Alex pulled his mind from his worries. He had to think about Simber’s question for a moment before he figured out what the cat was talking about. “Oh!” he said finally, and then his face clouded. “Oh, that’s right—Spike,” he said, remembering, which only added fuel to his worries. “Spike Furious. Um, yeah. Remember my whale sculpture from the Museum of Large that I brought to life the other day? I know you were watching. Anyway, she swam away, and that stupid eel captured her, too. That’s who he put in the glass cage earlier.”

Simber’s gaze never left the water, but his body tensed. “Does she brrreathe?”

Alex nodded. “Yeah, but she’s a whale, so she needs the water—”

“She’ll die in the cage, Alex. She’s going to need airrr.”

“What?” Alex asked, confused. “She nearly died from too much air in the museum. I had to . . .” He glanced at Sky, who stared at him, mouth agape, and the terrible feelings of failure became fresh all over again. “I had to put her to sleep and transport her to the water first.”

“You what?” Sky asked, incredulous.

“No, no, no!” Simber said, frustrated. “Whales need to be in the waterrr to surrrvive because they can’t move on land. Theirrr bodies arrre so heavy, they’ll crrrush themselves and overrrheat. So if you crrreated herrr as a brrreathing crrreaturrre, which it sounds like you did, she can only live a shorrrt time without any airrr.” Simber ended his sentence in a growl of frustration. He swished his tail.

Sky shook Alex’s shoulders. “Why didn’t you tell me you brought her to life? All this time I’ve been wondering, and you never said anything.”

Alex looked from Simber to Sky, feeling helpless about what to do now. “I don’t know,” he said anxiously. “I was really sad about it. And embarrassed. I nearly killed her by accident before she got away. I didn’t feel like telling everybody, okay? I didn’t want to let you down.”

Sky stared at him, speechless. She shook her head. “So that’s why . . .” She trailed off. There was no time for this conversation. “I can’t even deal with this right now.”

Alex gripped his knees and leaned forward, his head next to Simber’s neck, straining to see through the water. “Now what? How much time does Spike have?”

“I don’t know,” Simber muttered. “Maybe thirrrty or forrrty minutes. We need to get herrr now . . . while she still has a chance.” Simber dropped lower, just above the water, and stared down, trying to see if Octavia was coming back. “Alex?” he prompted. “What’s the plan?”

“Just let me think!” Alex couldn’t look at Sky. Where could Ms. Octavia be? Spike couldn’t wait. But what was happening down there? What if Ms. Octavia needed help? He dug the heels of his hands into his eye sockets and wished that someone else had to make the life-or-death decisions for once. After a measured breath, he spoke. “Okay,” Alex said quietly. “We’re going in. I need everybody on the ship standing by. Now.”

Simber soared back up. “Coverrr yourrr earrrs,” he said to Sky and Alex. When they did, he bellowed at the top of his voice, “Ahab! Brrring forrrth the ship!”

Alex, still stunned by the news of the time-sensitive threat to Spike, grew more fearful about Ms. Octavia’s lengthening disappearance, because she could drown too. He knew there was only one choice . . . but how best to do it?

“All right, then,” he said, ripping his fingers through his tangled hair and looking over his shoulder at Sky. “It’s happening. Are you ready?”

“What’s happening?” Sky asked.

Alex hesitated. He was still figuring it all out himself. “Okay, so . . . Simber, I say we send one team down to find Octavia and the others, and another team to rescue the sea creatures and Florence. We do it simultaneously. Maybe it’ll cause confusion and we’ll be able to pull it off.”

Simber nodded. “You think like a leaderrr,” he said. A grim compliment.

Sky was quiet. Waiting.

Alex sat up a little straighter and peered into the darkness. “Is Ahab coming?”

“Yes,” Simber said.

“Tell him to call all hands on deck and be prepared for rescue. Send the squirrelicorns here now.”

Simber did so. When he was done, Alex looked at Sky for a long moment, and that’s when the last piece fell into place. He knew how it would go now.