It takes thirty minutes to disarm a sonic mine. It takes the Doctor one minute, because she's brilliant.

She has twenty seconds.

The sonic mine is in a black case full of red flashing lights. Adds a nice sense of urgency to the situation that the Doctor could really do without.

"I'm sorry," she whispers, because she has twenty seconds and that isn't enough. She doesn't know if sonic mines interfere with the regeneration process. Could calculate it, run the numbers in her final seconds. But it won't change anything, because humans are fragile. They don't regenerate. They die.

Yaz, Graham, and Ryan are going to die. They're on a junkyard planet in a junkyard galaxy. No one here to help them. In this century, the average human can survive a direct sonic mine blast if they receive top-notch medical attention within twenty-two point nine three minutes. That's not going to happen.

"What's he found?" Yaz says from behind her. She doesn't know yet; of course, she doesn't know. She's not supposed to be on this planet, certainly not this century.

There's going to be a universe without Yaz, now.

Graham and the Doctor are closest to the sonic mine, one having found it, the other having investigated. Yaz and Ryan are behind them. Jumping on top of a sonic mine doesn't change much, but two bodies in the way might have a slight effect. The Doctor places Yaz and Ryan's available time at twenty-five point three two minutes before they will be beyond medical help.

"Nobody move," the Doctor says, waving her sonic screwdriver at the sonic mine. Her sonic screwdriver's brilliant—it fixes everything, so it has to fix this. She has to fix this. She has to save her friends. "If I can keep it in a temporal lock…" Calculations run through her head. Thousands and thousands of numbers arranging themselves into patterns, equations, answers. "No, it's got too many sensors, it won't work." They're going to die. On a junkyard planet. In the middle of nowhere. She sort of wishes that it could have at least been the Daleks. The Doctor had wanted to die fighting the Daleks, not getting blown up by a sonic mine.

Of course, there's the possibility that she'll survive this. Her friends will die and the Doctor will go back to the TARDIS. She'll stay away from Earth for a while—she can't face Yaz's family, tell them that Yaz is dead. That the Doctor killed her.

She thinks it might be better if Time Lords can't regenerate after sonic mine blasts.

"It was camouflaged," the Doctor says. She's just talking now—she loves talking. It's comforting, in a way, her mind filling with words. "This is someone's idea of a nasty joke."

"What is it?" Yaz asks, because Yaz trusts that whatever it is, the Doctor will figure it out.

"Sonic mine. It's counting down."

"How long we got?" Graham asks.

The Doctor wants to fix this, wants to save her friends. This can't be when she finally dies. This can't be what kills her new friends.

She's sorry, but she can't say it. The Doctor doesn't like apologizing, hates it actually. She can't even bring herself to say this just as they're going to die.

She brought them here. She killed them. And she's really, really sorry but she can't say it.

"Three."

Even as she stares down at the sonic screwdriver, the Doctor calculates trajectories. Her friends will be knocked unconscious right after the blast. They won't feel any pain. However useless it is, this means it's alright to optimize her friends' remaining minutes. It's not like she'll be prolonging their suffering.

"Two."

She can't throw herself over the mine—not enough time, not useful, pointless. Delete. But her friends will have their internal organs scrambled—they'll be extra vulnerable to any disturbance. She needs to, at the very least, not fall on them. She's closest to the blast. Good. If she regenerates, she regenerates, and if she doesn't, she wasn't going to anyway. Centimeters count for humans. They don't make a difference for her.

"One," she thinks as the white blast spreads outwards. The Doctor closes her eyes and hopes for a miracle.