Cover code #63821. This is a second printing or later, reprinting Ace F-325 (same cover art). Second book in the *Forerunner/Warlock* series. Other novels in this sequence: *Storm Over Warlock* (1960), *Forerunner Foray* (1973), *Forerunner* (1981) and *The Second Venture* (1985).
A young girl who has been sold as a slave to a trader wishing to do business with the Wyverns who rule the planet Warlock soon finds herself not only in contact with these strange beings but also involved in a mysterious internecine struggle she does not understand.