George Surridge, director of the Birmington Zoo, is a man with many worries. An outbreak of disease threatens the animals in his care. Stuck in a dry and loveless marriage to a high-maintenance woman, and addicted to gambling, he is in a perpetual financial crisis. He's scraped by for years waiting for an inheritance from an affluent elderly aunt. And when he falls for another woman and takes her up as his mistress, he finds the need for wealth even more pressing: with the inheritance, he can start life anew with his lover in a small cottage. As Surridge's debts mount and the pressure on him increases, he begins to dream of miracle solutions. Could he really commit the most devious murder in pursuit of his goals?