The Doctor (David Tennant) lands on Mars in 2059, near the first Martian colony, Bowie Base One. He puts on a spacesuit and walks to the base, where he is detained by Captain Adelaide Brooke (Lindsay Duncan). During the interrogation, he discovers that this is a fixed point in time, which cannot be changed. The base will explode, killing the entire crew, but the death of Adelaide Brooke will inspire her granddaughter to explore the stars. He tries not to have any influence on events, but Adelaide forces him to assist her when they get an alert from a remote biodome.

Two crewmen, Andrew Stone (Alan Ruscoe) and Tarak Ital (Chook Sibtain) are in a zombie-like state, producing large amounts of water from their bodies. One of Adelaide’s team is infected, and they quarantine her behind glass, temporarily. It seems the infection is caused by an intelligent virus called the Flood, which was used by the Ice Warriors long ago, and it got into the colony because of a faulty filter. The remaining crew have not been infected and Adelaide orders them to evacuate to Earth and sets the base to self-destruct. Before leaving for the TARDIS, the Doctor tells Adelaide why he can’t get involved.

Before getting to the TARDIS, he hears cries for help. The infected crew have broken the seal and are attacking the Central Hub with huge amounts of water. The pilot of the rocket is infected, but he causes it to self-destruct, killing himself and isolating the crew. The Doctor races back and rescues Adelaide—also Yuri (Aleksander Mikic) and Mia (Gemma Chan)—with the TARDIS. He returns them to Earth, arriving outside Adelaide’s home. He begins to enjoy the power of changing the future, but Adelaide is horrified by him and kills herself. The Doctor is shocked. But Yuri and Mia still know what happened. Ood Sigma (Paul Kasey) appears in the street, which the Doctor takes as a sign of some sort. He asks the Ood if it is time for him to die but gets no answer. Back in the TARDIS, he refuses to die and takes off.

This episode was called excellent by reviewers and won the 2010 Hugo Award. A trailer was shown at the 2009 San Diego Comic Con. Bowie Base was named for David Bowie, who wrote the song Life on Mars. The glasshouse scenes were filmed in the National Botanic Garden of Wales. It was filmed at night so as not to have blue skies in the background, but when they turned on the camera lights, hundreds of birds woke up and began chirping, so they had to write them into the script.

The Doctor’s spacesuit is the one from The Satan Pit. Helen Mirren was sought to play Adelaide Brooke but refused the role. The cute robot, Gadget, which was the only thing the reviewers hated, was based on Wall-E. The water monsters were toned down, considered too scary for the kiddies, and the water flowing over the actors’ faces made it to difficult to talk. Being the only survivor of the Time War seems to have gone to the Doctor’s head. He has gone from the Last Time Lord to the Time Lord Victorious and begins to sound like the Master.