These cousins began their careers as a publicist for the movies and as an art director for a New York ad agency. Just for fun they entered a mystery-writing contest under a single, assumed name. They won the contest and went on to a writing collaboration under a pen name that was perhaps the most successful, and lucrative, such partnership in all detective fiction. For years their true identities were concealed, e.g. a masked figure would appear at autographings. Name the cousins and their nom de plume.

All entries (one per person) must be clearly written on postcards and mailed to: Book Bag, The Washington Post, Washington, D.C. 20071, and must include complete return address and competition number. The winning entry will be the first correct answer drawn at random. Employes of The Washington Post Company and their families are not eligible to enter. Entries must be received no later than July 2nd. The winner's name and city of residence will be announced in the July 12th issue of Book World. A Washington Post Book World book bag, and a children's book, will be sent to the winner.

Answer to Book Bag #422: The names of the novels with the word "summer" in the titles are given after the names of the authors who wrote them: (1) Edith Wharton, Summer (2) P.G. Wodehouse, Summer Lightning (3) Aldous Huxley, After Many a Summer (N.B. -- American title: After Many a Summer Dies the Swan) (4) Doris Lessing, The Summer Before the Dark, and (5) John Crowley, Engine Summer.

Winner: Sophie Korczyk, Alexandria, Va.