Whilst financier, James Ryder, (Harry H. Corbett) discusses a potential take-over deal, he is unaware that Mrs. Cragg (Peggy Mount) is busy polishing the floor beneath his desk. After Ryder leaves, Mrs. Cragg retrieves an un-smoked cigar from the wastepaper bin, wraps it in a crumpled telegram, and takes it for her next cleaning client, Colonel Whitforth (Robert Morley). The Colonel gladly accepts the cigar, but is even more excited by the contents of the telegram, which allows them to make a cool £5,000 on the stock market! However, Mrs. Cragg feels uncomfortable with her easy gains and visits Mr. Ryder's office in order to give him the money back. But when she finds out that the city financiers want to use her street for development, Mrs Cragg decides that they have to be stopped. With the help of fellow cleaners, Mrs. Merryweather (Dandy Nichols), Mrs. Higgins (Miriam Karlin) and Emily Parish (Avril Elgar), the ladies who do take on the city gents at their own game!