“Brian the Brain” is episode five of season two of Space: 1999.
Dr Russell is dictating the status report; the full record of their travels is being reviewed and the computer is fully engaged. So, she and Commander Koenig are flirting when there’s a report that the Moon is changing course. The review is cancelled, but they can’t find a gravity source influencing them and can’t see anything either. Tony suggests a black dwarf and an evacuation is ordered. Then something appears on the screen. It’s not what’s pulling them off course.
Maya estimates it’s no larger than a small planet. Given it’s a spaceship, it’s a heck of a lot smaller. Eagles 1 and 2 are sent to intercept; Fraser doesn’t detect any unusual gravity. They hail the ship and it responds cheerfully, saying they are Eagles and is that the Moon? He’s also from Earth; he left on a mission in a mothership with three other Swifts in 1996. Alpha confirms there was such a mission. The Swift asks if Alpha is still there and manned and contacts them directly, asking if he can come down for lunch.
The Swift lands and Dr Russell, Koenig and two security officers head to it. The ship seems to be empty, then the voice that hailed them says he’s coming out. And a robot detaches itself from the console. The robot says the other Swifts and the mothership landed on a planet, Planet D. And they all died. He’s been waiting ever since. The robot says he’s the talking head, the brain, the rest of him is the computer on the Swift. He remains in contact with his antenna. In the travel pod, the robot is asked his name. He doesn’t have one, but the first word he spoke was Brian, not Brain. Brian is a name.
When asked about the gravity, Brian says he might be able to help. In the command centre, Brian cheerfully greets everyone. He looks at the computer and says it’s the same model as his. Brain invites the doctor on a tour of the Swift; maybe she will be able to throw a light on the death of his crew. The commander asks if he can come and Brian agrees.
When they leave, Maya says she has a bad feeling about this. She asks Tony to open a channel to the Swift. Which is now taking off. Brian is going to take Dr Russell and Commander Koenig to Planet D. He tells Koenig if Koenig kills Brian, the airlocks will open. If they make a move towards the spacesuits, Brian will let the air out. If Koenig puts the gun down, Brian will let them communicate with Alpha, and tell them what he’s doing. Brian says he isn’t going to harm them. Rather undermined by the threat to kill them both if Koenig doesn’t put down his gun.
Alpha is having problems with their computer; it looks like Brain messed with it. The apparent death of Brian’s original crew is now looking a lot more suspicious. Somehow, they need to stop Brian and restore their computer.