When a court ruling once again halts the carrying out of the death sentences of hundreds of condemned murderers, a frustrated vigilante organization decides to take matters into its own hands. In a mysterious and grisly act of horror, San Quentin's entire population of condemned prisoners is executed in the dark of night. But how? And who are these vigilantes? Answering those questions falls to retired FBI agent Cliff Knowles, now a successful lawyer. His lover, Special Agent Ellen Kennedy, is intent on completing a geocaching challenge known as the Fizzy Challenge, but inadvertently turns Cliff into suspect number one by going for one cache too many. She has no doubt Cliff is innocent, but he's kept a secret from her. He's kept a secret from everyone - and he knows that her faith in him is misplaced. His only chance of keeping Ellen in his life, perhaps even of staying off death row himself, is to get to the critical evidence before the FBI does.