Roger Fee and Vera Dardani travel to the cloud-enshrouded planet of Grenard to search for Vera's former husband, who has foolishly chosen to investigate the aboriginal Dryads, a vicious race of cannibals.They venture individually into the dark jungle, hoping that stealth and camouflage will keep them safe during the frightening journey to a dryad settlement. Both are stalked, and Vera faces multiple dangers.On arrival they are frustrated by both the dryads and a representative of the Multi-World Council, and must give up their search. Some persons, they begin to believe, are engaged in a criminal conspiracy, and they've unwittingly come too close to exposing it.Uncertain what they are up against, half-starving and desperate, they flee through the jungle, their lives threatened by relentless invisible creatures.