A Six Letter Word for Death — Patricia Moyes

When Henry Tibbett receives an anonymous crossword puzzle in the mail, he assumes it is just a prank. But when, bored with a slow summer, he begins to fill in the empty squares, he realizes he may have something deadly on his hands. The answers are the names of friends and relatives of people who have died under suspicious circumstances -- and one of the clues warns that more deaths may follow. The names in the puzzle lead Henry to the annual meeting of an exclusive organization of mystery writers who seem obsessed with one subject: murder.