One of the few "Rim Worlds" books that does not feature John Grimes - the first of 2 books about Derek Calver. Once of the Interstellar Transport Commission, he joins the Rim Runners to be second officer of Lorn Lady. He runs into Sonya Verril, sometime agent of the Federation Secret Service, and has a series of adventures on worlds of the Rim, including an encounter with the Rim Ghost ship Outsider.

This is expanded from "To Run the Rim" (Astounding January 1959.)