Mrs. Cragg and her neighbours in Pitt Street, Battersea, are cleaners in big City office blocks. Mrs Cragg also 'does' for Colonel Whitforth, an impecunious gambler.

Early one morning she is under a desk cleaning the floor when businessmen James Ryder and Sydney Tait arrive and begin discussing a potential take-over. After their departure she salvages a cigar for the Colonel, wrapping it in a discarded telegram. Whitforth is extremely thankful for the top-quality cigar, but even more when he realises what it is wrapped in - and the information the telegram contains! Using the newfound knowledge to his advantage, he doubles a £5,000 investment within a few hours and splits the money 50-50 with Mrs. C.

Reasoning that there's no possible way of making so much money so quickly, Cragg resolves to tell Ryder what they have done. However, on arriving at his office she overhears that he has just bought Pitt Street and intends to move her and her friends out of London to new towns and replace the neighbourhood with two huge office blocks - she quickly decides not only to keep the money, but play him at his own game!

Joining forces with three of her closest friends - Emily Parish, Mrs. Higgins and Mrs. Merryweather - Cragg and The Colonel form a new speculating company, Ladezudu, rifling through the rubbish collections from their regular office cleaning routines. After a number of successes they soon have more than £120,000 banked; with a couple of further crafty deals, it'll be enough to buy Pitt Street back.

Meanwhile, Ryder's associates have heard of the residents' unwillingness to leave their homes and are threatening to pull out of the redevelopment deal, which would leave him seriously indebted. Tait has already dissolved their partnership and James is at such pains to ensure work begins imminently that he heads to the site himself. Fearing their newfound fortune will not come through, the ladies put up a show of force and neither Ryder's workmen's pneumatic drill nor the Metropolitan Police Force can stop these women on a mission.