Synopsis: Strange fast-growing plants break into a bank which is then robbed by some dryads. A passerby, Henry Chalmers, is arrested for the crime. Chalmers hires Jean Loring to defend him and investigate his story.
Jean visits a retired horticultural expert, Walter Dudley, but is put to sleep by some flowers. The Atom, who has followed Jean, then follows some dryads back to Jason Woodrue. Atom learns that Woodrue is an exile from an interdimensional world inhabited by the dryads. He has imprisoned the queen, Maya, and now controls them as well as his advanced plants.
Atom frees Maya and together they try to prevent Woodrue's takeover of the world. Woodrue's plant creations threaten cities, but Atom manages to subvert the man's control and force him to surrender. Woodrue is then turned over to the authorities, and Chalmers is released.