Helen Martin was guarding a time experiment at UNIT when she felt the world lurch. She knew it was the Third Doctor's fault, so she went to his building. Inside she saw the Brigadier and Liz Shaw, unmoving.
She has spent the last five years in what she originally thought was a time loop where it is always 11:15 a.m. on 22 July, and no one and nothing move. However, she is able to move from place to place, and time is passing, so she rejects the loop theory. She can sleep and eat, and she can affect small things that are near her. She has worked out a routine whereby she sleeps for eight hours, and goes to UNIT headquarters in the morning to see if the doors have opened. She has noticed that things are starting to change slightly from day to day. One day she sees raindrops falling sideways, up, and down, and realises that she is moving through time sideways, that is, she is experiencing other versions of 22 July.
Meanwhile, Liz is worried about Helen, who is missing, and tries to get the Doctor involved. She thinks the Brigadier suspects that Helen has defected to the Soviet Union.
Mark has spent the last several years caught in time. He had experienced things dimming and had a feeling of nausea. When it passed, the drilling that he had heard constantly had changed pitch. He spends his days watching television or reading the paper, and spends a lot of his time drunk. He has noticed things are starting to change slightly from day to day.
The Doctor and Liz have realised that the Doctor's recent trip sideways in time must have affected Helen, as she was in the area during the experiment.
One day, Mark is making his way down the street when he sees someone — Helen — moving as well. She sees him too. They try to call out to each other and run to each other. Helen tells him they only have five more years of this left, then they fade away from each other. Helen has worked out that she is moving sideways towards his time, and he is moving sideways towards hers. They will be in the wrong realities, but it has to be better than what they are experiencing now.
- By her own reckoning, Helen lived in Maida Vale for around five years.
- Mark was a Republican Security Forces soldier in the parallel universe.
- The stories in Short Trips: Zodiac are inspired by the signs of the zodiac. This story's theme is Cancer.
- Parts of this story are told through Liz's journal.
- Liz is sceptical of the Doctor's claim to have recently visited a parallel universe. (TV: Inferno)
- In both universes there is a daytime chat show on the BBC Chorley's People hosted by Harold Chorley. (TV: The Web of Fear)
- Liz refers to the Daily Chronicle journalist James Stevens. (PROSE: Who Killed Kennedy)
- Liz tells the Doctor that Brigadier Lethbridge-Stewart is "a bit of maths whizz on the quiet." (TV: Mawdryn Undead)
- The Brigadier refers to the Primords as "werepeople." (TV: Inferno)