"Release the Doctor - or the killing will start." An asteroid in the furthest reaches of space - the most secure prison for the most dangerous of criminals. The Governor is responsible for the cruellest murderers so he's not impressed by the arrival of the man they're calling the most dangerous criminal in the quadrant. Or, as he prefers to be known, the Doctor. But when the new prisoner immediately sets about trying to escape, and keeps trying, the Governor sets out to find out why. Who is the Doctor and what's he really doing here? And who is the young woman who comes every day to visit him, only to be turned away by the guards? When the killing finally starts, the Governor begins to get his answers.