Catherine Gehrig is a middle-aged horologist working in "the Georgian halls" of the Swinburne Museum, London SW1.

Her boss Eric Croft moves her to the museum annexe in Olympia and gives her a recent acquisition to assemble: a complex mechanical toy that she first thinks might be a monkey, then decides is a duck.

Croft's hope is that Catherine will be led towards recovery by "the huge peace of mechanical things".

This story, which is told in sections that alternate with Catherine's own, involves Henry Brandling, scion of a wealthy 19th-century railway family, husband of sourpuss Hermione and father of sickly Percy.

When Percy falls ill, and all the usual Victorian therapies have failed, Henry becomes convinced that a foreign and mechanical entertainment might heal him.