It revolves around the science fiction writer's world. The now-dead author Fowler Foulkes has reigned over the science fiction world in much the same way as Sir Arthur Conan Doyle and Holmes have presided over mysteries. His son, Hilary, fiercely protects the intellectual property of his father and does everything he can to keep that property producing the money to go along with the popularity. Hilary's attitude of inflexibility and greed has also earned him many enemies--especially among his father's science fiction colleagues. There are a couple of "accidents" that make him think that his life is in danger...and then a man named Jonathan Tarbell is murdered. Tarbell's death is connected to the Foulkes family by a rosary found in his pocket. The police are called in and Detective Inspector Terry Marshall arrives at the Foulkes home at the same time as a box of chocolates...a box of chocolates that seems to be ticking. And then there's a locked room mystery to be solved.
This was the first Boucher mystery I read. I didn't find the earlier work Nine Times Nine (to which this is a sequel) until much later. It isn't the all-time best mystery. It's a competent mystery and a fairly competent locked room mystery--but having read John Dickson Carr first spoiled me for greatness. What was so great about this book was that I read it during my transition period back to mysteries from science fiction. And the book revolves around the science fiction world. Authors of the Golden Age of SF are represented here...and those who know their SF lore will recognize them--and will catch all the in-jokes. It has been said that this book was Boucher's attempt to introduce SF to the mystery loving crowd. I would say that it might work just as well the other way around.