A mysterious letter. A locked-room murder. And a secret that someone will kill to keep buried.
When detective Mara Ellison receives an unsigned letter sealed in crimson wax, its message is chillingly simple: her client is already marked.
The trail leads her to Blackwater House, where wealthy Mr. Vale has been found dead inside a study that appears to have been locked from within. But Mara soon discovers that nothing about the crime is as impossible as it first seems. A concealed mechanism, a missing key and traces of the same crimson wax point to someone who knew exactly how the murder was staged.
Then the investigation leads to the Rookwood Print Guild, a falsified paper trail and a mysterious ledger connected to Vale's death. Witnesses disappear. Evidence is deliberately altered. And a second crimson letter bears Mara's own name.
As Mara and her partner Pike dig deeper, they uncover an old network of hidden messages, secret passages and buried identities. But the closer Mara comes to discovering the truth, the more dangerous the investigation becomes.
Because the crimson letters were never simply warnings.
They were invitations.
And someone has been waiting for Mara to open the door.