Following the events of "Black Colossus", Conan leads a small band of warriors to rescue King Khossus of Khoraja from his Ophirean captors. Their quest is progressing unusually well, which raises Conan's suspicions. Soon, Conan discovers that one of his comrades is an agent of the enemy, and realizes he will have to go it alone on his quest.
References
Laughlin, Charlotte; Daniel J. H. Levack (1983). De Camp: An L. Sprague de Camp Bibliography. San Francisco: Underwood/Miller. pp. 238–239.