Dieter Fox, a skinny university student who along with his unnamed friend (who I'm assuming is the author) live together as the modern Holmes and Watson. Dieter is a great fan of detective novels and his home is a library filled with them. Soon there is murder in the University and Dieter gets a chance to play the detective. A friend of Dieter's, is accused and arrested by the Police, he engages Dieter and pleads with him to do his own investigation and find out who is the real killer and get him off the hook.
Dieter has his task cut out, he now has to find the real killer among half dozen suspects, get his friend out of jail and stop the murderer before the killer can play out his/her machinations.