Raymond Ellis is behind bars. The case should be over.

Then another woman disappears.

Sabrina Holt vanishes in the same pattern that defined the investigation against Ellis-only this time, Ellis is locked inside a county jail. Thirty-one hours later, Sabrina walks out of the woods alive with a message for FBI profiler Nasir Knox: the man who released her knew his name.

As Ellis's trial approaches, Knox and his team are forced to reopen everything they thought they understood. A missing fourth key, buried police history, compromised evidence, and a second presence hiding inside the original case begin pointing toward a disturbing possibility: Ray Ellis may have been guilty-but he may never have been working alone.

With the clock running toward trial and another predator still moving, Knox must separate what the evidence proves from what everyone has simply accepted as true.

Because sometimes catching the killer doesn't end the case.

Sometimes it reveals the one standing behind him.

The Fourth Key is Book Two of the Nasir Knox Thriller series by KVNG LEE.