There wasn't just one hole, though, the whole thing was riddled with holes and red herrings:
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The disappearance of the children was set up as a big mystery right from the start, but it was never resolved.
We never even found out what happened to Adam (and neither did he).
The only connection between the children in the woods and the later murders was that the murdered girl's father was one of the youths in the woods on the day the children vanished.
The motorway, and his objections to it, was another irrelevant sub-plot.
We never found out -and no one seemed to care - who "Lexie" really was or why she had taken a new identity, she was just dismissed and thrown away.
How the girl knew that Rob was Adam was a mystery.
At the beginning, Adam and Cassie both seemed to be sharing some secret knowledge of the woods, but in fact the long-ago incident was nothing to with Cassie, was it?
Then at the end, Rob and Cassie agreed that they must never meet again - but why?
And as for the wolf.....
To me, it was just a lazy narrative in which the author enjoyed setting up little mysteries and conundrums but couldn't be bothered to provide answers.