Patricks son Charlie has left home in disgrace. His zoologist wife Jane is on a field trip in Zaire and his daughter Jo is engrossed in her studies. So Patrick is left alone to look after the ailing Devonshire monkey sanctuary that he and Jane took on in a bid to save their marriage. Alone, that is, but for the big, panther-like cat that preys around the park, evading capture, lurking in the shadows and in the back of Patricks mind as he tries to uncover the truth behind the murder of their oldest female primate. Patricks fears begin to fade. But then one night something happens that is so shocking, so deplorable, that it rips apart everything he ever held to be true - and unleashes a horror he could never have imagined...