Adam Robert "Rob" Ryan Timeline & Summary

In 1984, young Adam Robert Ryan and his two friends, Peter and Jamie, go into the woods. Only one returns: Rob.
Twenty years later, Rob is a detective on Dublin's Murder Squad. He and his partner, Cassie Maddox, investigate the murder of Katy Devlin.
Twelve-year-old Katy was murdered in the same woods Rob's friends disappeared; he wonders if the cases are related.
Rob and Cassie interrogate suspects and do general detective work. You've watched TV. You know how it works.
Along the way, Rob tries to recover some of his repressed memories, even spending the night in the woods to jog his memory.
He remembers that Jonathan Devlin, Katy's dad, and his two friends once gang-raped a girl in the woods.
They investigate Jonathan. He may be a gang rapist, but this doesn't make him a murderer.
While this is going on, Rob sleeps with Cassie, then starts treating her badly for no real reason.
Eventually, Rob remembers one of the archeologists was missing a trowel. They find the trowel, and it leads them to Damien Donnelly, the archeologist who killed Katy.
Damien confesses that he was in a relationship with Rosalind, Katy's sister, so Cassie puts together a sting to get Rosalind to confess to masterminding the crime.
Rosalind ends up exposing Rob's true identity as Adam Ryan to the police, and Rob is demoted.
He also loses his friendship with Cassie because he's a jerk.