Yuri apologizes to Maggie in her sickbay cell as he packs the place up. He turns off everything and the system lights go red -- it's even spookier, now -- and she slowly makes her way over to the sickbay doors, fusing them or whatever. The cameras go to static while the rest of the crew stares, hoping she won't come after them. In sickbay, having dispatched the door easily enough, Maggie smiles. Then she begins to scream.
Andy and Tarak head back for the main dome as Adelaide and the Doctor stare down at the ice fields. "They tell legends of Mars, from long ago," he explains, "Of a fine and noble race who built an empire out of snow. The Ice Warriors." I've never seen them, but I've been told I would like them. "Perhaps they found something down there," he continues against Adelaide's protests. "Used their might and their wisdom to freeze it."
Meanwhile, Adelaide's more focused on the story in front of her -- the trees, right, her crew, the idea that stories end and she does not -- and gets more and more irritated by him. Because the point isn't how the Flood got down there, or why it came back up again, but how the water process must have been changed at some point, and how that can date the infection and say who's safe and who is not. The Doctor tries to help, knocking against the screen, as Adelaide considers him.
"You don't look like a coward. But all you've wanted to do is leave. You know so much about us..." The Doctor fakely says it's because they're so famous, but she knows there's more. He takes one look in those stern, lovely eyes, and knows she won't let it go. They keep working, and he tries to explain about fixed moments. "Tiny, precious moments. Everything else is in flux, anything can happen, but those certain moments, they have to stand. This base, on Mars, with you, Adelaide Brooke, this is one vital moment. What happens here must always happen."
She knows enough to get worried now: "Which is what?" He lies, twisting one way and another, desperate to be anywhere else, hearts moving in separate directions, every instinct screaming at him to run, leave, disappear, except the highest one of all. So he lies instead. "...I don't know." He looks at her face: "I think something wonderful happens." She swallows as he looks at her -- who she is, has been, will be -- and sees her all at once. The Time Lord's burden. "Something that started fifty years ago, isn't that right?" She stares; she's never told a soul. "You told your daughter. And maybe one day she tells the story to her daughter. The day the Earth was stolen and moved across the universe. And you...?"