Driven to desperate measures, local businessman Christopher Hancock and the Reverend Phillips persuade the starving villagers to wreck a ship in order to loot its cargo to eat or sell. Unfortunately the ship they wreck is a floating asylum (a ‘ship of fools’) and because the villagers have superstitious natures (they believe it is very bad luck to kill a fool) they are forced into a position of care for the three remaining survivors.

These three are revealed to be Billy (who speaks in riddles); the foulmouthed Mary, and a mute, Henry. Hancock and Phillips try to resolve the situation; they can’t kill the survivors, they can’t let them go and so they have to feed them from their already dwindling supplies. The audience discovers that Henry was the doctor on the ship. Hancock takes Henry away from the other two captives to be examined by the Rev Phillips (who is also the village doctor). Hancock then returns to try and make amends for his actions. Mary insults and berates him, goading him into violent action and becoming the victim of a rape that Billy witnesses, but Hancock himself (even as the perpetrator) cannot watch.

Henry discovers the rape and in his anger accidentally reveals his true nature to Hancock and Phillips. He is taken to the vicarage where he is interrogated, during which he reveals the truth about the ‘ship of fools’ and his place on it. In order to save money, his previous community closed their asylum and abandoned the inmates to the waves.

Hancock kills Henry, and the Rev Phillips, now aware of Mary’s rape, turns against him and tries to help the two remaining survivors escape. The play ends at an impasse with Phillips imploring Hancock to let them go and do “One good thing …”

The play was initially envisaged as an allegory of the arguments against 'Care in the Community' (ie the abandonment of seriously ill patients and the lack of round-the-clock care) however the period setting allows for various other readings.