How did this creep get in here, Professor? was a short story written by Peter Darvill-Evans. Originally written as a sample first chapter for the Virgin New Adventures line, it was passed over in favour of PROSE: Timewyrm: Genesys, which left a longer gap between the end of TV: Survival and the beginning of the Seventh Doctor and Ace's prose adventures.
As Ace and the Seventh Doctor make their way back to the TARDI, they discuss where they want to go next. The Doctor replies vaguely that he "hasn't quite decided yet," and expresses his hopes that, wherever they'll go, they won't bump into the Master again.
As Ace comments, these prove to be "famous last words," as, when they enter the TARDIS control room, they find none other than the Master himself. The Doctor speculates that, since he "had to go somewhere" after the Cheetah Planet ceased to exist, yet calls no place home, he was deposited in the TARDIS due to its being "a piece of Gallifrey on Earth" and thus a passable compromise. The Master instead posits that it was thanks to the strength of his desire to travel through time and space freely once again.
The Master reveals that he has removed the TARDIS's Identity Recognition Module, which means she no longer recognises the Doctor as her only pilot, and will also respond to the Master's commands. The Doctor has to stop Ace from physically assaulting the Master, who goes on to explain that he knows the Doctor probably has spare modules, but is confident that he won't be able to install them in the short time before the TARDIS reaches the Master's intended destination.
So saying, the Master sets the controls, and then uses his hammer to damage the console, making it impossible for the Doctor to alter the coordinates. He then disappears into another room of the TARDIS; the Doctor and Ace cannot safely follow him because only the Doctor's bond with the TARDIS let him navigate its winding labyrinth of corridor safely, and he is now afraid of getting lost. Sitting in the control room, the two resign themselves to wait and see where the Master has decided to take them.
- TARDIS keys pick up fingerprints and other biochemical data which are transmitted to "an offshoot of the central computer," which only then lets the doors unlock.
- Without her Individual Recognition Module, the TARDIS will not let the Doctor access her data banks.
- The Master uses a hammer to damage the Time and Space slide controls on the TARDIS control console.
- The Doctor is bonded to his TARDIS permanently, in a way which goes beyond the Individual Recognition Module; he states that this is part of the Rassilon imprimature.
- This story presents one of many conflicting fates for the Master after the events of TV: Survival. Other, conflicting accounts of it were given in PROSE: First Frontier and PROSE: The Eight Doctors.
- The Doctor, Ace and the Master have just finished their struggle against the power and dangers of the Cheetah Planet. (TV: Survival)
- The Doctor mentions the Rassilon imprimature. (TV: The Two Doctors; PROSE: Interference - Book One)