Beloved as the herald of spring, cuckoos have held a place in our affections for centuries. The oldest song in English celebrates the cuckoo's arrival, telling us that 'Sumer is icumen in'. But for many other birds the cuckoo is a signal of doom, for it is Nature's most notorious cheat. Cuckoos across the world have evolved extraordinary tricks to manipulate other species into raising their young. How do they get away with it? In this enormously engaging book, naturalist and scientist Nick Davies reveals how cuckoos trick their hosts. Using shrewd detective skills and field experiments, he uncovers an evolutionary arms race, in which hosts evolve better defences against cuckoos and cuckoos, in turn, evolve novel forms of trickery. This is a fascinating corner of Darwin's 'entangled bank', where creatures are continually evolving to keep up with changes in their rivals. Lively field drawings by James McCallum, and remarkable photographs, show cuckoos in action: from the female cuckoo laying her beautifully disguised egg, to the cuckoo chick ejecting the host's eggs and young from the nest to ensure it gets the full attention of its foster parents. Cuckoo offers a new insight not only into the secret lives of these extraordinary birds, but also into how cheating evolves and thrives in the natural world.