One of the delights of the locked room concept is its flexibility. You can adapt it for horror books, historical dramas, postmodernist fiction (see the Umberto Eco book below), or even science fiction—as Isaac Asimov shows in this pulp fiction novel from 1954. Asimov himself viewed science fiction in the most expansive terms—so I suspect he took particular delight in constructing a detective story set many centuries in the future. Adding to the fun, a human detective and robot investigator compete with each other in attempting to solve the mystery.