When two of Kate Ivory's friends, members of a team working at an Oxford University biotechnology unit, start to receive smoke bombs through the letterbox and discover that slanderous letters about them are being circulated, Kate is intrigued and disturbed. Working where they do, her friends are used to the high security necessary to ward off animal activists. But this time there is a difference: there is nothing random in the choice of victims, and the attacks are growing more sophisticated. The team is in danger of being disbanded and if this happens the important project they are working on will come to an end. Is this just another phase in the war between scientists and the Animal Liberation Front or is there a different - and dangerous - group at work? And if so, do they have an ulterior motive for trying to sabotage the project? Novelist and amateur sleuth Kate is persuaded to find out who is behind the dirty tricks, before her friends' careers, and even their lives, are put at risk...