Following the Jack Grant and Tom Deaton series, No Exit features a new series protagonist: FBI Special Agent Gwen Harrison. Introduced in Poison Touch, Gwen is a native American, descended from distinguished ancestors, including a warrior who fought beside Enchanted Horse (Gwen's correction of 'Crazy' Horse). She is an amateur tracker whose avocation becomes a dangerous obsession. After a bloody altercation in a San Francisco alley she decides to channel her energies and skills in more constructive ways by joining the Bureau.

After leading her class at Quantico and achieving some dramatic wins in the midwest Gwen elects to escape the local media glare by relocating to the New York field office, where her skills are quickly employed in a major terrorism case—Operation Huis Clos—one that reaches its bloody climax in the heart of the nation's capitol.