From a louse that replaces the tongue of a fish to a legion of larvae that dramatically burst out of a caterpillar, and parasites that infest the eyestalks of a snail - some creatures stop at nothing when it comes to using other animals for survival. These bizarre and often unpleasant relationships reveal the darker side of nature's ingenuity. Biologist Dan O’Neil delves into this strange world of alien invaders, uncovering the fascinating and sometimes horrifying tactics these parasites use to thrive.

From mutant frogs with extra limbs to a freaky fungus that take over the brains and bodies of bullet ants, and even a male anglerfish that transforms into a set of testes - nature is full of very strange and disturbing surprises. When it comes to staying one step ahead in order to endure, sometimes only evil genius will do. Biologist Dan O’Neill dives deep into this weird and wonderful world, revealing the extraordinary and sometimes terrifying ways in which nature has evolved to survive.