Exactly at the title describes: a murder mystery set at the annual American Booksellers Association convention. Asimov attended the convention under contract with Doubleday with the express intention of developing a novel from that milieu. Because the publisher wanted to promote the book at the following year's convention, Asimov was given just three months to write it.
Although Asimov goes to great lengths in an afterword to deny that any of the major characters are based on real persons, his narrator, Darius Just, is clearly modeled on Harlan Ellison. The book (which is also dedicated to HE) is an interesting bit of metafiction, with Asimov himself making several appearances and the two of them -- Asimov and Just -- trading barbs via footnotes throughout.
As for the mystery story itself, it is mildly clever though hardly suspenseful, told in real time over the course of the four-day convention, mostly through dialogue that eventually becomes tedious. And the book reflects (and to some extent revolves around) conventional mid-1970s attitudes toward gender and sexuality, which seem quaint at best today.
