Prisoners on the High Rock, who have no rights whatsoever, are stripped of their last name and instead referred to by the number of years to which they have been sentenced, hence Harry's prison moniker. Other prisoners include Harry's fiery-tempered cellmate, the Mongolian Genghis Eighteen (who is killed in an escape attempt); the deranged Old Ben Ninety (who is eventually revealed to be an android spy for the Warden); the brutal Big Red One, a psychopathic killer who has been jailed for one hundred years; and the sycophantic Twenty-One Toady. They are under the heel of the vicious prison guard Pusser, the guards' leader Chief Thrower and the sinister one-eyed Warden Worldwise, clad in a long black cloak (it gets chilly in outer space), who is very much in the spirit of a James Bond villain.
It is implied that hardly anybody, regardless of the length of their sentence, ever gets off the High Rock alive since the punishment for most infractions can be death, depending on the whim of the guards. After several failed escape attempts, Harry and Big Red One lead a revolt. Their insurrection leaves the High Rock in the hands of the prisoners but spiralling out of Earth orbit into deep space, albeit with a self-sustaining environment and enough supplies to last them all for two decades. Harry announces that they now have a chance to build a new life for themselves free from the fascist authorities on Earth.
Finley-Day says that the series was inspired by Escape From Alcatraz (the 1979 Clint Eastwood film) and the novel Papillon by Henri Charrière. It was reprinted in Judge Dredd Megazine #209-213, in The Best of 2000 AD Monthly and in the American format 2000 AD Presents (published by Quality Comics). There has also been a collected edition, and in 2015, 2000 AD Free Comic Book Day Vol 1 5 gave us a somewhat unexpected one-off sequel story, Death Rock, which showed us where Harry and his comrades ended up.