Eight-year-old Jack, his seven-year-old sister, Annie, and Peanut the mouse ride in a tree house to the Amazon rain forests, where they encounter giant ants, flesh-eating piranhas, hungry crocodiles, and wild jaguars.

Left stranded in the Amazon jungle when their plane crashes on their way back to England from Manaus, Brazil, four children struggle to survive for days until one of them finds a map that leads them to a ruined city and a secret hidden among the vines.