The four remaining relatives of famed practical joker Henry Russell are brought together to hear his last will and testament, with a possible inheritance of £50,000 each if they can all complete an unusual challenge. The assignments are designed to reflect their greatest shortcomings, test their abilities to adapt and ultimately change for the better. Law-abiding retired army officer Deniston (Alastair Sim), secretly writes scandalous novels until he is given a week to get himself arrested for an actual crime and jailed for exactly 28 days. Haughty Agnes (Fay Compton) must find employment as a housekeeper in a middle-class home and retain her position for a month despite her disdain. Simon (Cuy Middleton), a penniless womanising rogue, would have to marry the first single woman he speaks to, such as the cigarette girl at the club he frequents (Audrey Hepburn). Finally, timid Herbert (George Cole) must hold up the bank he works at for two minutes with a mask and a toy pistol. Can they each conquer their task and grab the cash?