When Matt Brandon is accused of killing Henry Clark, he sends for his old friend, lawyer Carson Drew. Carson's sixteen-year-old daughter Nancy is convinced that her father can clear Matt's name--with her help. Shortly after their arrival, Carson obtains Matt's release from jail on the grounds that no body has been recovered. Later, Nancy and her friend, Ted Nickerson, discover a rare tropical flower on Matt's land. Nancy sends Matt's servant, Apollo Johnson, to dig the plant up for her, and he discovers Clark's body buried underneath. Now the police have everything they need to keep Matt in jail. Because she feels responsible for his arrest, Nancy decides to solve the mystery herself. She is sure that the rare plant grew from a seed that was dropped at the time Clark was buried, a suspicion that is confirmed when she learns that Clark's partner, Clinton Griffith, has a nursery on his property. She and Ted sneak into Griffith's greenhouse to look for the rare plant, but before they can find it, Griffith returns. Learning of their intentions, he asks his pilot, Chuck Marley, to follow them, and Marley overhears them make plans to look at the nursery's sales records the following day. That evening when the Drews accept neighbor Edna Gregory's invitation to an ice cream social, Marley sets the nursery on fire, and the records are destroyed. Nancy talks Ted into searching Griffith's barn for the missing murder weapon, and they find the gun just as Griffith discovers them. He locks them in the barn, planning to kill them in a fake accident. They escape by waving a scarf in front of a bull, but Marley then blocks their path with his airplane. Meanwhile, Apollo has informed Edna of Nancy's plans. She fetches Carson in time to see Ted and Nancy abandoned in the now airborne airplane. After Ted manages to land the plane, Carson explains that Griffith and Marley were robbing Clark and killed him when he discovered their duplicity. Matt is freed and Nancy is reconciled to her father's romance with Edna.