Back at university, Dominic made a drunken pact with Lucy--if neither of them were married by 35, they would marry each other. Now they are 35, and they are wondering if it could actually work. Dominic moved back to London to find out, but Lucy is a single mother and doesn't know whether to take him seriously. The proposal would be ideal had she not tried marriage once before, and were their sex not quite so bad. Can friendship be redesigned to make a marriage?