Shutter Island
I think this had me questioning everything tbh. The plot twist of Teddy Daniels truly being Andrew laeddis taking up a fake identity to cope with grief was chefs kiss.
The ending was so so tragic though when he appears to relapse back to being Teddy and appears to give himself in. But the crazy thing is when he says to 'Chuck' "would you rather die a good man or live a monster" implying that he is fully aware of his true identity but chooses to 'escape' his life of grief and 'manipulate' himself into thinking he is a good man in his final moments.