"Deathworld" by Harry Harrison is a science fiction novel first published in 1960. Professional gambler Jason dinAlt wins an enormous fortune and travels to Pyrrus, the deadliest planet ever colonized by humans. Every creature, plant, and microorganism actively tries to kill the human settlers, who are slowly losing their battle for survival. Jason discovers the planet holds dark secrets about why everything attacks the city—and why some humans living outside remain safe. He must solve the mystery before the colony dies.