Barkeep, by William Lashner

The hero of this novel is Justin Chase, a law school graduate who tends bar because the horror of finding his mother murdered took him over an edge from which he never returned.   Unable to engage with others, Justin pretends that his Zen practice is stabilizing (oddly, it is built around his reading of the Book of the Dead).   Justin's father was convicted of the murder.   Now, someone brings information to Justin which implies that his father was not the murderer, and Justin follows a trail of interaction that leads to the unfulfilling denouement.   Characters are poorly developed and shallow in description.

The Barkeep