It's the dawning of a new era. US Air Force Colonel Lloyd Beadle unveils his British space travellers for the press, whose imaginations go into overdrive when they learn that one of the crew is a woman. But Beadle has another ace up his sleeve: Bimbo, a mongrel dog.

In their orbiting space station, the crew members are trying to acclimatise themselves while rapidly discovering each other's foibles. Sleep eludes them, and they realise that privacy is a thing of the past...

Gentian's in charge of the Life Science Projects, and David's doing Earth Observation, Astronomy, Crystallography and Communications — leaving Malcolm doing the dusting. And not terribly well. It takes a major crisis before the Mission Commander finally comes into his own.

Earthly problems invade the space station and Gentian Foster believes she knows why: Ackroyd's being beastly because he doesn't fancy her, and Mattocks is being patronising because he does.

After five weeks of constant surveillance, relations between the crew and Ground Control are strained. So when Beadle disappears for lunch, the astronauts decide to get even.

Fifty days in space should be newsworthy, but the media has already lost interest. Beadle promises to remedy the situation. Ackroyd, however, is more interested in the potent product of his lab experiment involving yeast, fruit flies and a copious quantity of blackcurrant juice...

Nine weeks into the mission: depression is rampant. The food is boring. The routine is boring. Then, catastrophe! A wiring fault plunges the station into darkness. With Mattocks and Ackroyd out of action, Foster must rely on Bimbo to save her.

Gentian finds herself talking to the machinery while Ackroyd quite happily holds conversations with himself. Mattocks is concerned about both of them and discusses it with the only person he can trust — Bimbo.

Ackroyd denounces the whole mission as a big publicity stunt. Mattocks, meanwhile, has been caught out acting furtively and sending scrambled messages. Gentian and Ackroyd want to know what's happening but it's top secret...

Mattocks is pining for his wife but he gets no sympathy from the other two, who are determined to see that he lives up to his domestic responsibilities while he's at the space station. Beadle has a hot date.

Ackroyd is concerned that he is now maintaining some of the systems beyond their level of tolerance — emergency repairs are now the norm. During one of the blackouts Gentian sees a bright object outside her lab window.

One week to go and the crew breaks the record for the longest spaceflight in history. Beadle is ecstatic but Mattocks is behaving more strangely than normal, questioning things at a cosmic level — much to the annoyance of the other two.

After six months, the mission is completed and it's time to go home. Mattocks' recent epiphany still annoys the other two, and concern over re-entry has caused group insomnia. Ackroyd doesn't want to go home.