The Beasts of Valhalla

A detective takes on mad scientists when a D&D fantasy world turns deadly in this “ thrilling combination” of “not-quite-science-fiction and suspense” (Playboy).
 
With a genius IQ, a past career as a circus acrobat, and a black belt in karate, criminology professor Dr. Robert Frederickson—better known as “Mongo the Magnificent”—has a decidedly unusual background for a private investigator. He also just so happens to be a dwarf.
 
When Mongo’s sister asks him to investigate the death of his nephew, Tommy—the victim of an apparent murder-suicide—the private detective soon learns that everything’s tied to the computer game Tommy and his friends created: an elaborate quest based on J. R. R. Tolkien’s The Lord of the Rings. The clues send Mongo on a cross-country journey, from a painful visit to his former hometown in Nebraska and back to New York, then on to the rugged coastline of California’s Big Sur and, ultimately, the frozen depths of the Arctic Ocean, where a mad genius will stop at nothing to achieve total Armageddon.
 
Grounded by his completely original private detective Mongo, author George C. Chesbro “writes wonderfully strange mystery novels” (Boston Sunday Herald).
 
The Beasts of Valhalla is the 4th book in the Mongo Mysteries, but you may enjoy reading the series in any order.