Outwitting Trolls - William G. Tapply

Brady Coyne is a Boston attorney who focuses on a few private clients and the legal drudgery of their everyday life, which leads to a generally unexciting life. Brady, however, gets a call from an old friend and former neighbor—a man from his past as a happily married man.

When Brady was married and living in suburbia, Ken Nichols was his happily married neighbor. Both marriages fell apart years ago and Brady moved to Boston while Ken Nichols moved to Baltimore. Now a decade later and in Boston for a conference, Ken contacts Brady for a get-together and a drink. It's an uneventful evening but the next day Brady gets a call from Nichols' ex-wife. She's standing in her ex's hotel room, Nichols is lying dead on the floor of his room and she needs Brady's help.

But this savage murder is only the first and Brady is soon trying to find the connection between these long ago friends and the savage murders dogging their family.