Elton Pope (Marc Warren) sees a photo of the Doctor (David Tennant) during an alien invasion report by Ursula Blake (Shirley Henderson) on her blog. He recalls seeing the Doctor as a child. Elton and Ursula and some like-minded friends form a group called LINDA (London Investigation “N” Detective Agency) and meet in a library basement.
Eventually, a man named Victor Kennedy (comedian Peter Kay) appears at a meeting. He says he cannot be touched because of a skin condition. He wants the group to work harder at finding the Doctor and his companion Rose (Billie Piper) and teaches them spying techniques, as he takes over the whole club. Elton is tasked with getting close to Rose’s mother Jackie (Camile Coduri). He meets her at a laundromat and is invited to her apartment, because he’s young and physically attractive. Jackie fails to seduce him and finds a picture of Rose, realizing he was only trying to get close to the Doctor. She sends him on his way.
Two members named Bridget (Moya Brady) and Bliss (Kathryn Drysdale) disappear. Elton and Ursula discover that Victor is an alien which Elton calls an Abzorbaloff and has absorbed the missing people into his body. He is out to absorb the Doctor to gain his vast knowledge and experience. He absorbs Ursula and pursues Elton.
Elton is cornered at a dead end. Before he can be absorbed, the TARDIS materializes, and the Doctor and Rose appear. At the Doctor’s suggestion, the absorbed members use their willpower to supress the Abzorbaloff, who drops his cane. Elton breaks the cane and the Abzorbaloff melts into the ground, unfortunately taking the LINDA members with him, except for Ursula, who ends up a face on a paving stone.
The episode barely featured David Tennant and Billie Piper, which was the point. There were too many episodes scheduled and they needed something that would not take up too much of the lead actors’ time. It was called Doctor-lite and companion-lite. Several more were done in the future, some of them very good. This one, not so much. It featured a lot of flashbacks and used footage. The Doctor and Rose are in it less than ten minutes. Jackie has more screen-time. This trick was being pulled as far back as the ailing First Doctor William Hartnell, who needed time off occasionally. The same thing was done in other series, notably Buffy and Star Trek: The Next Generation. Shirley Henderson (Ursula) was Moaning Myrtle in the Harry Potter movies. The chase scene in the beginning is a parody of Scooby Doo.
The Abzorbaloff was designed by a nine-year old kid named William Grantham as part of a contest on TV. The creature comes from a planet near Raxacoricofallapatorius (where the Slitheen come from) called Clom. Comedian Peter Kay was originally supposed to play Elton, but that role was similar to a character he had just played on Coronation Street and he wanted to play the bad guy. He regretted it later. The episode received some good reviews and a lot of vitriol. Of 200 Doctor Who episodes at the time, Doctor Who magazine readers put it at number 153. In another poll, it was 220 out of 241. On the plus side, the relationships among the members of LINDA are nicely done, both sad and charming until the monster shows up. And of course, if you get a kick out of gross humour, you have a lot to like.