To pull off a daring diamond heist in Rio during Carnival, a retired schoolteacher hires four professionals who must contend with a revolutionary alarm system and a taciturn secretary.

After retirement, Professor James Anders presents criminal Mark Milford an elaborate plan to rob a diamond company in Brazil with a crew of professionals. The men assemble in Rio de Janeiro and run in to an unanticipated problem: a new alarm system called Grand Slam 70.—FV