Sam, Gus and Jack are hunting for monitor lizards when Andrew calls Sam inviting her to the mainland university to give a lecture to his medical students. Sam can’t see the value in going to the mainland and is provoked when she overhears a rival researcher criticize her venom work as a hobby. A honeymooning couple from the Backpackers finds a magical swimming hole with a deadly secret lurking beneath the surface. The new bride steps on a stonefish, and Sam and Rick argue over whether or not they should give her anti-venom. The discovery of the stonefish habitat offers Sam and Gus a new, exciting venom project, but Sam has to figure out a new way to extract venom from a stonefish without killing it.