The series follows the adventures of Maine game warden Mike Bowditch. The first book explored Mike's upbringing and his strained relationship with his n'er do well father, who was accused of a grisly murder. Trespasser takes place several months after the events of that book and starts with Mike trying to reconcile with his girlfriend, who sees his outdoor lifestyle and poor-paying job as roadblocks to their relationship.
Called to the scene of an accident in which an out of town motorist hit a deer, Mike is surprised to find the car abandoned and the deer gone. A complex series of events eventually turns into a murder mystery with startling similarities to a decade old murder case which resulted in the conviction of a man named Erland Jefferts. Many in the community believed that Jefferts was innocent and this new crime may give them the ammunition they need to seek a new trial.
As in his first book, Doiron dives deep into the psychological makeup of his characters and chums the waters with enough red herrings to keep the reader unsure of the identity of the killer until the final few pages. Unfortunately, it is in those pages that the plot comes somewhat off the tracks. I understand what Doiron was trying to do; offer a nuanced resolution rather than a tidy one, but the supposed motive of the accomplice in keeping the secret didn't make any sense to me. As a result, I'm going to give this one a C+. It's a good effort and entirely readable, but gets bogged down in its own ambition at the end.