Keith Laumer is not new to science fiction and was an old pro who had written some of the best and most humorous science fiction adventures stories ever written. His best works are from before 1970 but wrote some interesting works until his passing in 1990.
Greylorn is a fun romp but if you want to read his best, try the Retief stories as well as Time Trap, Dinosaur Beach and Earthblood,
I'd just like to add that Sherlock Holmes is well-known for his incredible deductions skills, however this is a falsity. It is much more occurent in the The Adventures of Sherlock Holmes that Sir Conan Doyle employs the use of Induction, not Deduction, in his main character Sherlock Holmes. The difference is that deduction is drawing two points of fact to draw a conclusion; however, Sherlock Holmes often induces based on fact and experience to surmise conclusions. If you read some of the most famous of Sherlock Holmes quotes, you will notice this pattern.
Thank you, I just needed to point that out. Bar none best detective novel you can read. It left an indelible impression on me, as a student.
This is hair raising horror a la E.A. Poe - no blood and gore, just that bone chilling fear of knowing their is a presence of something terrible just beyond the trees...