Kiss Me, Dudley by Ed McBain

I picked up a copy of The McBain Files at a library sale, and this is the first McBain I read. Kiss Me, Dudley is a seriously deranged story. A woman walks into a PI's office and normal ends there. Her mate has caused her trouble by stealing 10 million and dying leaving her at the mercy of the people he stole from. Before the initial interview is over, the PI has belted his client. Before it's all over, the PI will have struck his client several times (and done worse) and gotten rid of the enemies - all 26 of them. With grenades... Bizarre and well worth the read.