Recently, scientists at the frontiers of biology have hypothesised the existence of life-forms that can only be called "weird": organisms that live off acid rather than water, microbes that thrive at temperatures and pressure levels so extreme that their cellular structures should break down, even organisms that reproduce without DNA. The search for these strange life-forms spans the universe, from the Martian permafrost, the ammonia oceans of Jupiter's moons, the hydrogen-rich atmospheres of giant planets, the exotic ices on comets and the crusts of neutron stars. David Toomey brings us into the world of the researchers who have devoted their careers to "weird life". As they envision and discover ever stranger organisms here on earth, they open up fascinating possibilities for the discovery of life in the rest of the universe.