I've been rewatching the Bond films recently, and I realised that a fairly common theme is that many of them have a really strong first hour or so then suddenly decline in quality and go out with a whimper - sometimes they go completely off the rails, sometimes they go nowhere, sometimes they jump the shark massively. Examples: Thunderball - great first hour with an intriguing plot and genuinely engaging characters - then it descends into endless underwater sequences and nothing much else, and by the end is intensely boring. Moonraker - it does not need the space sections at all. I wouldn't say the first hour is great, to be honest, but it's a hell of a lot better than what follows, which is basically a poor man's Star Wars. Quantum of Solace - in the second half of the film, all the most interesting characters disappear to varying degrees, the film rushes into a half-baked conclusion, and the final scenes are a mess. And it got me thinking about other films that do this - I would say Indiana Jones and the Kingdom of the Crystal Skull, Spider-Man 3, and The Island all go completely insane in their second half after relatively enjoyable first halves. What other films would you suggest and why?