10 Weird Movie Plot Twists That Just Don't Work

10. Laurie Is Michael's Sister - Halloween II

The Set-Up: the 1978 original established that homicidal maniac Michael Myers breaks out of a mental institution and returns to his hometown of Haddonfield to go on a killing spree, 15 years to the day after killing his own big sister. The first film ends with him seemingly shot dead, but then mysteriously vanishing; the sequel, set later that same night, sees him to come back to get final girl Laurie (Jamie Lee Curtis) in the hospital.

The Twist: it turns out Michael wasn't just out to kill random teenagers that Halloween night: he was specifically targeting Laurie, because - although she didn't know it - she is actually his little sister!

Why It Doesn't Work: Admittedly there's a lot about Michael Myers we need to take with a pinch of salt: how does he know it's Halloween, know how to find his home town, or know how to drive a car when he's been catatonic since he was 6?

The fact that he also knows this girl he's never met is his sibling, when almost no one else is aware of this, is a stretch too far. Worse yet, it robs the original of much of its mystery.