Cut Me in — Ed McBain

When a Man's Partner is Killed, He's Supposed to Do Something About It. 

Maybe no one liked Del Gilbert a whole lot, not the men he ruthlessly did business with, not the women who discovered his other lovers, not even his partner in the Gilbert and Blake literary agency -- me. But when I found him shot to death on the floor of his office, I had no choice. I had to track down the person responsible. And not just to lay Del to rest, either. Next to his body, the office safe was wide open, and a contract worth millions was missing...