Which movie is a story about a gang of diamond thieves who double-cross one another?

A 'Fish Called Wanda' was a 1988 British-American heist comedy film about a gang of diamond thieves who double-cross one another to find stolen diamonds hidden by the gang leader. This was director Charles Crichton's last movie starring Jamie Lee Curtis, Kevin Kline and Michael Palin, and John Cleese.

The film was nominated for 3 Academy Awards including Best Director and Best Original Screenplay, winning Best Supporting Actor for Kline. Cleese and Palin won British Academy Film Awards for Best Actor and Best Supporting Actor for their performance.

The plot has multiple instances where the characters double-cross one another and betrayal occurs multiple times as each person tries to gain an advantage in pursuit of the diamonds. An example is when the con artist Wanda and weapons expert Otto pretend to be siblings when they are really lovers, so Wanda can work her charms on the other male members of the gang.

On 'Rotten Tomatoes', an American review-aggregation website for film and TV, the film held a 93% approval rating, based on 61 reviews, with an average rating of 8/10. The site's critical consensus read, "Smartly written, smoothly directed, and solidly cast, 'A Fish Called Wanda' offers a classic example of a brainy comedy with widespread appeal."

After 6 weeks of a wide release in the US, it reached number one at the box office. It eventually grossed $62.5 million in the US (2019 = $135.3 million) and was the number one rental video in the US in 1989.