A family murdered; an undercover police officer assassinated. Detective Nate Grimes is tasked with solving these seemingly unrelated murders.

There's a young witness to the murder of the family. However, the witness has amnesia. As Grimes works to protect the witness, he discovers there's a malevolent presence lurking in the shadows. A presence that will do whatever is necessary to keep its existence secret – including murder.

Now both his and the witness's lives are in danger, unaware that their greatest threat is within the police force itself.