It's kitten season in Cambridge, and the results can be murder.

Becca is coming home from her job at Charm and Cherish when she sees a kitten dodging cars on Mass Ave. She follows, only to see the kitten run down an alley. Becca follows when suddenly a bright light illuminates what turns out to be a dead-end. Before her, a strangely familiar body is on the ground--her ex boyfriend, Jeff. And right beside Jeff, the kitten is staring back at her. Becca scoops up the kitten and shoves her into her bag, before turning to face the police.

The police received a call about a man and a woman arguing viciously, including threats of violence. Since the body is that of Becca's ex, she comes under suspicion. But more motives than jealousy soon emerge: Jeff was working on stealth software designed to record and transmit personal data - a new form of spyware that would be of interest to everyone from the police and security agencies to cybercriminals. Even as the police investigation appears to have moved on, Becca realizes she is under surveillance. And when Jeff's former friends and colleagues approach her, Becca finds the police aren't the only ones watching her. When a particularly secretive tech guru clumsily approaches, apparently trying to romance her, she enlists the aid of a contact from the local hacker group. Through him, she comes to realize that Jeff may have installed an early version of his software on her computer - and that it contains enough information for a knowledgeable IT geek to reproduce the finished result.

Meanwhile, Becca is sheltering the little tortie - and her three magical cats are horrified. The tortie isn't of their lineage or their family. And yet she seems to have some powers of her own, which may help Becca discern friend from foe, solve Jeff's murder, and clear her name - with the help of her mystical feline friends.