Reporter Terry Brewer goes to the Los Angeles airport to say goodbye to his sweetheart, airline hostess Rita Moore. He notices G-Man Mike Phelan among the passengers and assuming Phelan is on the trail of a criminal, decides to go along to get a story. When the plane makes a stop in New Mexico, passenger Mrs. Tristo buys a hunting knife from an Indian. Late that night, a shadowy figure approaches the sleeping Ramon Duval and plunges a knife into his heart. Phelan assumes charge of the situation and begins to question the passengers. Wanda Terrell, who is wanted-fugitive Killer Madsen in drag disguise, holds up Phelan and announces he is now running the show. He orders pilot Bob White to head the plane to Evansville, Indiana, Masden's hometown. When Rita offers Masden a cup of coffee, which includes a powerful sleeping potion, the suspicious Masden exchanges cups with co-pilot Johnnie Martin who passes out.
