Owen's voice cuts out abruptly, and is replaced instantly by Gwen's, loud and alarmed. "Jack, code zero incursion. Repeat, code zero incursion. We're under attack!"

Jack grabs his gun out of its holster, checking its loaded almost without thinking as he turns to Toshiko. "If you don't hear from me within fifteen minutes, activate total shutdown procedures and get yourself to safety," he says, voice grim, and starts downwards.

"But I can't just leave you all here!" she protests, looking small and frightened behind her workstation.

"If there's a Cyberman in this building," he says, as calmly as he can, "We need a last line of defense. Just make sure it never gets to the outside world!"

Then he runs for it, unwilling to waste another second which could cost Owen and Gwen their lives.