Going by the wikipedia entry, the book seems to make it unambiguous that Jacob was the killer all along, though his death at the end was more an accident.I enjoyed the car crash part - I was completely shocked by it & it added suspense to the whole story - I thought they were both dead. The ending let me down. I would’ve liked to know who killed that kid. Apparently the book ending is completely different to this. There was too many questions at the end of it, which annoyed me.
Personally, I would rather have the series end with both mother and son dying the crash, or leaving their fates unknown. Too many loose ends at the end. So does the mother believe in his son's innocence now or not? Either way, life will never be normal again for the entire family.
And well, Chris Evans is a powerful draw either way.