Dead Aim (Thomas Perry)

Mallon is a retired builder who has lots of money but no real life - he spends his days walking aimlessly along the Santa Barbara shore. One day he sees a young woman walk into the ocean, and he pulls her out and tries to convince her not to take her own life. A few days later he finds out he failed, and becomes obsessed with finding out who she was and why she believed she had to die. His search takes him to an exclusive self-defense school in the mountains, and from there he finds himself fighting for his life. The action is gripping, and the author made it almost plausible that the mild-mannered protagonist could succeed over a cadre of highly-trained killers. I enjoyed it.