This could have been one of the ultimate thrillers had it not been for the final act.
The first 3/4 of the film was intense, intriguing, kept you guessing, had me completely clueless...it really needed a clever ending to match with everything that had been thrown at the viewer.
Instead it gave us an elaborate explanation, piece by piece of how the whole story fit together, not leaving any doubt, told by one of the characters just sitting there telling the story to another of the characters. It felt lazy compared to the rest and it's a real shame.
Despite the lame ending, I really enjoyed the rest of the film and François Cluzet is so cool and such a great actor. I wish there had of been more KST.