Mrs Wilberforce is a sweet and eccentric old widow who lives alone with her raucous parrots and likes to report suspicious behavior to the police. Unaware of her reputation, the dapper thief Professor Marcus rents rooms in the elderly widow's home for himself and his band of cohorts. Posing as a string quintet, the thieves pull off a bank robbery, but slip up in front of the old woman as they try to escape.