As David's Italian penpal, Mario, is coming to stay, his wife Kate goes to her mother's so that they can practise their languages in peace. When the penpal turns out to be a shapely brunette named Maria David is in big trouble, not least because Maria has smuggled in a packet of diamonds. The flat is soon besieged with assorted gangsters, a lady plumber, a curate, the police and an angry Kate!|5 women, 6 men