Fairly good espionage novella. The plot is contrived but entertaining. None of the characters really stand out, they are formulaic for the time. Persistent police, evil villains, and a woman in harm's way.
Space pulp, with most of the standard elements - the down-on-his-luck space pilot, the scantily clad space-babe with a mission. Throw in evil aliens in pursuit and how can you go wrong? Nothing deep here, but a decent time killer if you're stuck in a waiting room.
One of the best crime novels I have found on this site. Not really a "mystery", as the crimes are clearly portrayed. The four-way game between the intelligent criminal, peripheral criminals, pursuers, and victims is brilliantly written. I agree with the "6 star" comment, this book really stands out.
Another excellent Fletcher mystery. If you are a fan of British crime / mystery and have never read Fletcher, you owe it to yourself to give him a try.