The last time I heard this story was back in 2007, back in the happy days on YouTube before the BBC staked their copyright claim and closed down channels that posted Doctor Who. And there was literally everything on YouTube - from Hartnell to the previous day's David Tennant story, including the reconstructions of stories like Galaxy 4. Only a five minute clip exists of this story (from episode one), the rest is lost.
From now on until the start of season 6 (Patrick Troughton's last season), my Who reviews will consist largely of lost episode reconstructions - that I have recently heard/seen - as the complete stories are more the exception.
Season 3 fairs a bit better than seasons 4 and 5. Nineteen out of 32 episodes still exist; whereas season 4 has 9/43 and season 5 has 13/40 existing episodes.
Needless to say, socialist society wouldn't have these nonsense copyrights and barriers to people enjoying television shows or music. Apropos YouTube, music videos are being pulled off now.
But to Galaxy 4, itself....
The TARDIS arrives on a deserted planet where two spaceships have crashed after a battle. One is Drahvin (the Drahvins are blondes with big guns) and the other belongs to the Rills (who are called monstrous by the Drahvins and which possess robots that Vicki christens Chumblies).
The Drahvins rescue the Doctor and co. from a Chumbly and are taken to the Drahvin spaceship. The Drahvins are a largely female society - the men have certain purposes, but are normally killed because they use up precious resources. The only proper Drahvin on this ship is Maaga - the others are grown in test tubes, and are really mindless drones, who serve one purpose: to fight.
The planet is about to explode; the Drahvins want to capture the Rill spaceship because their's is damaged beyond repair. They force the Doctor and Vicki to get the Rills' spaceship; Steven is held captive.
Aboard the Rill ship, Vicki meets the blob like and telepathic Rills. They use the Chumblies to transmit their thoughts into spoken words. The Rills are sensitive, thoughtful creatures who have offered to help the Drahvins. The Doctor and Vicki decide to help the Rills. Aboard the Drahvin ship, Steven (who doesn't know the Chumblies are not hostile) is trying to escape from the Drahvins but dare not step outside. He is trapped in an airlock, which the Drahvins are emptying of air. However, the Doctor and Vicki arrive back in time to rescue Steven.
It turns out that the Drahvins are in fact evil, whereas the Rills are good. The Rills are quite prepared, in the eventuality, to die and let the time travellers leave in the TARDIS and save themselves because the ideals the Doctor stands for are those the Rills share and consider more important to preserve than themselves.
The Drahvins try a last ditch effort to escape but the Rill spaceship takes off and the TARDIS dematerialises, settling their fate.
Galaxy 4 trundles along but is nonetheless an interesting story. Writer William Emms develops two quite different alien species in the space of four episodes, the theme being the familiar beauty and the beast. The Drahvins are a sort of space age "Herland" or Amazonian species, with no redeeming features at all; the Rills, although more alien looking, possess a fine character.