Cold service - Robert B Parker

When Spenser's closest ally, Hawk, is brutally injured and left for dead while protecting bookie Luther Gillespie, Spenser embarks on an epic journey to rehabilitate his friend in body and soul. Spenser quickly learns that the Ukrainian mob is responsible for the hit, but finding a way into their tightly knit circle is not nearly so simple. As the body count rises, Spenser is forced to employ some questionable techniques and some even more questionable hired guns while redefining his friendship with Hawk in the name of vengeance.