The circle - Peter Lovesey

Encourged by his fourteen-year-old-daughter who recognises his lonely widowhood, Bob Naylor decides to join a writers' circle, believing he might gain some expert help with the poetry which keeps spilling out of his imagination. He discovers a motley collection of wannabe authors who he doubts he has anything in common with, but just as he is deciding not to formally join the group he learns that a publisher who addressed their last meeting has been killed and he stays to see what might develop.
The Senior Investigating Officer, Henrietta Mallin, soon has all the members of the group under suspicion and under pressure from her superiors arrests their Chairman. Bob, the only writer who had not met the dead man, is persuaded by some other members of the group to do some investigating of his own. And that is when the trouble really starts, because another death turns the spotlight of suspicion on to him.