Callisto is homeless. Her only friends are DI Harry Monroe and a penguin. When Harry is killed she'll do anything to find his killer.
Callisto is homeless. Her best friend is Nelson, a penguin that she has been seeing since forever and doesn't believe is a delusion. Apart from that she is perfectly sane and a valuable source of information to the local police. When Cally’s friend DI Harry Monroe asks for her help in tracking a missing boy she doesn't think twice. But when Harry is murdered in front of her while they look for the teen Cally is plunged into a world of organised crime and gangs with connections everywhere. The kid is a key witness in bringing down this gang and solving Harry’s murder. Something the local police don’t are unwillingy to believe. The only link between the crimes is a symbol appearing at the crime scenes. With no other choice Cally finds herself having to team up with Harry’s old partner, Sheldon – who she hates in order to solve his death. As they delve deeper into the case, more people turn up dead they realise there is a leak in the police giving information to the gang. With no alternative Sheldon has to rely on Cally’s dubious contacts to gain information as his own department has been compromised.