Just after the Earl of Severn has vowed that if the plainest, dullest, most ordinary female in England were to be set before him he would marry her without further ado, Abigail Gardiner calls on him at his town house. The strong-minded Abigail is a distant cousin of the earl's and has been driven, much against the grain, to seek his aid. To do so, she has decided to dress as plainly as possible and to act the part of a dull brown mouse. The inevitable inevitably happens!