During World War I, commanding officer General Broulard orders his subordinate, General Mireau, to attack a German trench position, offering a promotion as an incentive. Though the mission is foolhardy to the point of suicide, Mireau commands his own subordinate, Colonel Dax, to plan the attack. When it ends in disaster, General Mireau demands the court-martial of three random soldiers in order to save face.

Four men from different parts of the globe, all hiding from their pasts in the same remote South American town, agree to risk their lives transporting gallons of unstable nitroglycerin across dangerous jungle.

Burglar Nat Harbin (Dan Duryea) and his two associates set their sights on wealthy spiritualist Sister Sarah, who has inherited a fortune — including a renowned emerald necklace — from a Philadelphia financier. Using Nat’s female ward, Gladden (Jayne Mansfield), to pose as an admirer and case the mansion where the woman lives, they set up a perfect break-in. Things get complicated afterwards.