There are no reasons for unreasonable things. So the protagonists of this novel are told having found themselves setting out on an adventure that they really didn't plan. Like many people, Murdoch has always had a great affection for the two lead characters in Beckett's ‘Waiting for Godot’. Have you ever wondered what Didi and Gogo were like when they were young and what led them to end up waiting for a man who would most likely never turn up? That's basically the premise Murdoch set out to explore in Milligan and Murphy but that was not the question he finally answered.
Milligan and Murphy are not Didi and Gogo, nor are they Mercier and Camier, Beckett's less-well-known "pseudo-couple" — they are very much themselves — but after an unexpected encounter on the road out of the town with an old man who has decided that searching for someone that will never be found is better than waiting for someone who will never turn up, they suddenly find themselves with big questions to answer and they're not very good with questions, big or small.
On their journey they meet a variety of eccentric characters: a priest who in a former life was a Roman centurion, an artist who now walks with a limp after venturing into the ring with a boxing kangaroo, a former inmate of the local asylum and a bartender who might well be Old Nick himself. The question is, whereas Beckett's characters walk round and round in circles and get nowhere, will Milligan and Murphy escape or be dragged back home by the mysterious man who has been cycling after them?