Everything begins when Amy, Nick's wife, suddenly disappears. There are indications that an attack took place, perhaps even a murder - and perhaps even Nick! Nick is one of the narrators of the story - the other being Amy via the pages of his diary in recent years - and this is indeed a troubled voice than Nick, which puts the reader at ease evil and leaves us uncertain as to his guilt - at least in the first part.
'Gone Girl' is a good psychological thriller, well built, with its share of surprises, able to manipulate the reader, and taking from one end to the other. The very end is a bit disappointing, but the rest is worth some attention. So I recommend it.