The Betrayal: Too many to count, really. Dan (Jude Law) cheats on Alice (Natalie Portman) with Anna (Julia Roberts), who in turn cheats on Larry (Clive Owen).
Then they go round the mulberry bush again.
Why It’s So Bad: If there isn’t trust in a relationship, what is there?
That’s partly the point here, as our quartet flounder in their own self-perpetuated misery.
The Fallout: Everybody lives unhappily ever after. Lovely.
Dial M For Murder (1954)
The Betrayal: Resenting the fact that his wife Margot (Grace Kelly) had an affair, Tony Wendice (Ray Milland) hatches a plan to have her killed.
Why It’s So Bad: The meticulous manner in which Tony coldly devises his wife’s murder is chilling to the core.
The Fallout: The ‘murder’ gets botched, and Tony comes a cropper.
The Betrayal: In a fit of teenage angst, 13-year-old Briony Tallis (Saoirse Ronan) fingers Robbie (James McAvoy) for the supposed rape of Lola (Juno Temple), even though she knows he’s not the culprit.
Why It’s So Bad: Briony’s lie is borne entirely of sexual jealousy after she witnessed Robbie’s romantic affair with her older sister Cecilia (Keira Knightley).
The Fallout: Pure pain and misery.
The Betrayal: Weyland-Yutani representative Carter Burke (Paul Reiser) gets Ripley (Sigourney Weaver) and a military cartel to planet LV-426 under false pretences, then attempts to murder Ripley by trapping her in a room with a facehugger.
Why It’s So Bad: We’re talking about life or death here – in this case, death-by-facehugger.
Which is surely the worst kind of death.
The Fallout: Ripley and Newt are saved.
Burke’s branded a sweaty liar and eventually ends up killed by a xenomorph. Hurrah!
The Betrayal: A case of Cain and Abel, this one, as El Mariachi (Banderas) sets out to get revenge against Bucho (Joaquim de Almeida), the man who killed the woman he loves.
Why It’s So Bad: Why Cain and Abel?
Well, it turns out that Bucho is actually El Mariachi’s older brother. Doof.
The Fallout: Bucho eats led. Naturally.
The Betrayal: BEWARE, MASSIVE SPOILERS . At the end of Looper , rather than let his older self (Bruce Willis) kill a child, Joe (Joseph Gordon-Levitt) shoots himself in the head, effectively closing the loop and killing them both.
Why It’s So Bad: Sure, he saved the day, but Joe sort of betrayed himself in the process.
Not necessarily a bad thing, mind, when your future self is a child killer.
The Fallout: Happily ever after… we assume.
The Count Of Monte Cristo (2002)
The Betrayal: Edmond Dantès (Jim Caviezel) is framed and jailed for a crime that he didn’t commit by his best friend, Fernand Mondego.
Why It’s So Bad: Not only does Edmond end up in jail, the woman he loves (Mercédès) is told that he has been executed. Ouch.
The Fallout: After breaking out of jail, Edmond uses hidden treasure to become Count Of Monte Cristo and gain revenge for the wrongs done to him.
The Betrayal: James Bond (Pierce Brosnan) is double-crossed by 006, Alec Trevelyan (Sean Bean), who everybody believes to be dead.
In reality, he’s planning revenge against Britian for his parents’ deaths.
Why It’s So Bad: Trevelyan wants to take Britain apart with one fell swoop by crippling the country’s economy using the last GoldenEye.
The Fallout: Trevelyan dies. Bond wins. Of course.
The Fellowship Of The Ring (2001)
The Betrayal: Saruman the White (Christopher Lee) betrays his old friend Gandalf the Grey (Ian McKellen) by joining with Sauron’s forces.
Why It’s So Bad: The betrayal is bad enough, but then Gandalf’s beaten to a pulp and imprisoned atop Saruman’s tower.
The Fallout: Gandalf manages to escape (he’s a good guy, after all) and sets off to help Frodo (Elijah Wood) battle Saruman’s forces…
The Betrayal: When King Leonidas (Gerard Butler) turns deformed Spartan outcast Ephialtes (Andrew Tiernan) away, arguing he cannot use him as a soldier, Ephialtes joins the enemy instead.
Why It’s So Bad: Equipped with Spartan knowledge, Ephialtes informs the Persians of the secret path integral to the Spartan’s plan of attack.
The Fallout: A big, giant battle, to say the least.