Walter Smithers, 69, is a retired engineer and widower. He collects tiny morsels from London's pavements, parks and gutters and exhibits them at home. Finds include a grape pip, a ball bearing and the wing of a flying ant.

When his irritating son, troubled daughter-in-law and much-loved baby granddaughter come to stay, a sequence of events lead to Walter being thrust into the East End art scene. His son thinks he's out of control, but his daughter-in-law has found a kindred spirit and Walter discovers more joy and pain than he ever thought possible at his age.