Meet Penelope Whittaker. A sensible, do things the right way, soon-to-be-married accountant. Penelope is engaged to the wonderful, kind and caring Ben Miller ... a man she has known forever. Enter Single Dad. While on a school run, Penelope accidentally locks her keys in her car. A seemingly boring event, until she is offered aid by a very handsome (hubba, hubba) and personable Single Dad. Shaken by the encounter, or, more to the point, shaken by her reaction to the encounter, Penelope tries to put it where it belongs: on a shelf marked "Chance Encounters." Life has different plans.