The protagonists are the young Sylvia Thesiger and Hilary Chayne, a captain in the British army. After their first meeting on the Mont Blanc massif, Sylvia goes back to Englandto live with her father. Skinner proves to be a dangerous man with a mysterious past and Sylvia tries, with Chayne's help, to protect the designated victim. The final showdowntakes place on the fatal Brenva route, one of the most dangerous ways to reach the top of Mont Blanc.