Deathworld centers on Jason dinAlt, originally from an agrarian planet Porgorstorsaand, a professional gambler who uses his erratic psionic abilities to tip the odds in his favor. While on a gambling trip to the casino on the planet Cassylia, he is challenged by a mysterious man named Kerk Pyrrus to turn a large amount of money into an immense sum by gambling at a government-run casino. He succeeds and survives the planetary government's desperate efforts to steal back the money. In a fit of ennui, he decides to accompany Kerk to his home, despite being warned that it is the deadliest world ever colonized by humans.

