"What is...?" Jenny asked, spinning around. She blinked. Put her hand to her head.

Yimi backed away, uneasily. "What's wrong?"

Jenny dropped her hand and waved it away. "Probably nothing." She leaned down and pulled at the grating of the TARDIS floor. "I put my psychic defenses up at full, ever since that last mental invasion. I think I keep rubbing elbows with the Battle TARDIS."

Yimi, still a bit warily, helped Jenny to lift the grating and move it to the side. It clanged as they dropped it.

"At least it means I'm not getting taken over by the Apos'alu anymore," Jenny said, grabbing a torch out of the toolkit. She pressed a button on the underside of the floor, and a ladder extended downwards. "Come on." She hopped onto the ladder and began to climb. "Let's see what we're dealing with."

A minute later, Jenny leapt off the ladder and onto the gantry, shining her torch around to examine the bowels of the ship. "Oh."

"What is...?" Yimi hopped down after her. Then frowned. "Oh." Stared at their surroundings. "Is it supposed to look like this?" She walked forwards and touched the hard white substance that was currently engulfing the coral.

"Not as far as I'm concerned." Jenny shone the torch in the other direction, but found more of the same. "What happened here? It's like someone encased this place in a bar of soap." She wrinkled her nose. "Except it smells like rot and grime." She walked a little further, then shook her head. "Yimi — if you've still got that link open with Zeera, can you tell Dad what we found down here?"

Yimi went silent, closing her eyes for a moment. Then shook her head. "It's no good. Whatever they're doing on their side, it's sent Zeera's mind into turmoil. I can't break through."

Jenny walked over to the hard white stuff, touching it. "It really feels like soap." She tried to dig her fingernails into it. "Maybe we could scrape it...!" But it didn't scrape off. Didn't even scratch. "Oh well. Worth a shot."

Yimi peered into the darkness. "Wait." She ran further, gesturing for Jenny to follow her. "I see something!"

Jenny ran after her with a sigh, doing her best to redirect her torch in front of Yimi. Didn't she know how dangerous it could be down here? "Yimi, be careful..."

Yimi clambered down a set of steps in the gantry, and then spun around, her hands in the air. "See? It's different!"

Jenny rushed down the stairs after her... then slowed. Shone the torchlight around.

The coral was different, here. No soapy-looking substance. Instead, there was this brown, slimy stuff that glowed in the dark. It looked a bit like... kelp.

"Oh." Jenny slapped her head with her hand. "Oh, you are kidding me. It can't be the radioactive super-kelp. Tell me it's not the radioactive mutant super-kelp! That'd just be ridiculous!"

Yimi frowned. "Radioactive...?"

Jenny grabbed Yimi by the wrist. "Come on. We better get out of here." They began to run. "I don't have a Geiger counter on me, but I'm guessing that something called 'radioactive mutant super-kelp' is probably a bit radioactive."

Five minutes later, they were up top again, Jenny leaning over the central console and pouring over data about radioactive mutant super kelp.

Yimi took the pill that Jenny had given her. It tasted foul.

"You know, all the stuff Stenman-Hoyer is doing makes a lot more sense when you read the secret files," Jenny said. She hacked her way into another database and kept reading. "Well, the good news is, it looks like both the soap and the radioactive mutant super-kelp were just the latest in a long line of experiments in which Stenman-Hoyer was trying to do exactly what Dad wanted the two of us to do — unground the ship. Granted, Stenman-Hoyer didn't actually succeed, yet." A small smile trickled up Jenny's face. "But they were trying to get this ship to fly anywhere. And we only need it to go a very specific distance." She leapt into the air, excitedly. "Yes! Yes, that's it. Oh, I'm a genius!"

She spun around and dove for the toolkit, rummaging around and grabbing something.

"Two minutes!" Jenny called, climbing back down into the underbelly of the Battle TARDIS. "Then flip that green switch on the central console by the swivel screen." She leapt down onto the gantry, turning on her torch. "I've got a job to do."