The play consists of four short vignettes, each of which revolves around different individuals or groups of people locked inside a cage for the entertainment of paying visitors, reminiscent of a sideshow.
The Killer proceeds to deny that he has ever killed anyone and gradually draws Mr and Mrs Smith in, trying to persuade them that he stays in his cage so that people can come to him for help.
The Killer puts the bar back himself, shutting a panicked Mr Smith in the cage who starts shouting for help.
Concerned for her safety, and believing she now knows how the parents were killed, she calls Mr Jacob who insists that the weapons are just toys.
While Miss Jones is offstage retrieving a policeman, Jacob gets up, scolding Pinkie for firing the gun, but then realises that the resulting scandal might help to get the punters in.
Mrs Grey issues a stream of insults against her nervous husband for failing to fulfil the promises of a good life he made to her before they were married.
Jacob leaves to bring in the latest visitors and, in his absence, Mrs Grey further insults her husband, finally labelling him as pathetic.
In the final, poignant play, Mr Jacob brings the Lovely family to see a green man who is locked in the cage with his hands tied.
Jacob explains how the green man is not really human, although he may appear so, and is unable to speak or understand anything except basic commands.
Once the Lovelys have left, the green man sings about his captivity and his desire for release, through death, in a form reminiscent of a spiritual.
As Jacob leaves, Helen Lovely returns to bring the green man some food and is happy to learn that he is able to speak.
The following morning, Jacob enters with a policeman who orders the green man to confess to the rape and murder of Helen Lovely.
People in Cages was first produced by Michael Friend Productions at the Mill Studio, Guildford, England in February 2000.