Nothing is as it seems in this surreal jungle hideaway at the center of a story that shifts unpredictably from the tragedy of Orpheus to the mordant comedy of “A Handful of Dust.” The psychedelic plants might offer death or immortality; the natives are as likely to welcome strangers as they are to shoot them with poison darts. Patchett’s creation of this foreign culture and its symbiosis with the fauna of a lost world is one of the novel’s most captivating elements. And the hallucinatory side effects of malaria medication ensure that sleep offers Marina no escape from strange visions.

Loaded as the story is with profound ethical issues, Patchett also knows when to pack light to keep the adventure moving. In fact, as the end approaches, “State of Wonder” crashes toward a breathless conclusion as though she’s being chased by a swarm of Amazonian wasps. This is surely the smartest, most exciting novel of the summer.