Our narrator wants to "warn" us: He is a detective so, as he says, "I crave truth. And I lie" (1.4).
He tells us what happened in that little village from the prologue, Knocknaree, on August 14, 1984.
Three children—Jamie Rowan, Adam Ryan, and Peter Savage—all age twelve, disappeared in the woods.
When searchers found Adam Ryan, he had bloody socks, and the inside of his shoes were bloody, which means that the shoes were filled with blood when he put them on.
His T-shirt had four parallel tears, but Ryan was uninjured, though in a traumatized and near-catatonic state.
This being the 80s, there was no DNA testing, so they tested the blood's type: A positive. Ryan was also A positive, and so was Germaine (a.k.a. Jamie); Peter, however, was type O. Investigators wondered if the blood could have come from a fourth person.
Peter's wristwatch was found, but neither Peter nor Germaine ever were.
Now, in the present, Adam Ryan, who goes by Rob so people don't know he was the missing boy in the woods, works for the Murder squad, along with his partner, Cassie Maddox.
Even though she's a woman, and women are supposed to be terrible cops (at least according to all the male cops), Cassie is a good partner.
Here's how they became friends:
When Cassie was new, Rob found her stranded outside of work. Her Vespa had broken down, and it was raining; he "fell in love with her" (1.33) because she was hopeless and helpless.
He made fun of her for calling the throttle the "thingy" (1.33), and she immediately gave him attitude. "Ohhh, I've always dreamed of a knight in shining armor coming along and rescuing little me! Only in my dreams he was good-looking" (1.34). In Ireland, that is called an o'snap.
Rob says he "stopped falling in love with her and started to like her immensely" (1.35).