MARCIA MULLER & BILL PRONZINI – Double. St. Martin’s Press, hardcover, 1984. Mysterious Press, paperback, September 1995.

   I think that this may be the first novel co-authored by two MWA Grand Masters, but even so, my next thought was that perhaps it doesn’t count, since they weren’t Grand Masters when they wrote it. No, that’s nitpicking, I told myself. Of course it counts.

   Double is told in alternating chapters by their best known series characters, Bill’s “Nameless” PI and Marcia’s Sharon McCone. They’re both attending a private investigators’ convention in San Diego, when (of course) they come across several suspicious events, including the supposed suicide (by jumping) of a former mentor of McCone’s.

   Neither of them has a client, but neither can either of them sit back and let the police have all the fun. And reading this book is fun, with many a chapter ending as a cliffhanger, with the other character immediately taking over, totally unaware of what straits the previous author had left his or her fellow investigator.

   This must have a book that was fun to write as well, but even I as a reader can tell what challenges the authors had to face and overcome to make it work as well as it does. Incidentally, while neither character spends much time at the PI convention, they do see in passing there a female PI based in Santa Teresa, plus a couple of gents named Brock Callahan and Miles Jacoby, among others.