Kate (Emma Thompson) and Richard (Pierce Brosnan) are a divorced couple content to live their lives far apart as long as their retirement is comfortable. But when a sleazy French businessman, Vincent, bankrupts their company, they're ready to put aside their differences and get their money back. Trouble is, there's no legal way to retrieve the funds, and when Vincent literally throws them out of his office, they vow revenge. With the help of their obliging neighbours, Jerry (Timothy Spall) and Penelope (Celia Imrie), they hatch a madcap plot to steal a $10 million diamond the crooked Vincent has bought for his gorgeous fiancée. All they have to do is crash a wedding on an isolated island, sneak past armed security, and smuggle the diamond out without getting caught… if it works, it will be the ultimate payback.