"Do. Not. Miss. This. One!"--Ronie Kendig, bestselling and award-winning author of The Tox Files

US Secret Service Special Agent Luke Powell is lucky to be alive. Three of his fellow agents have died in unusual circumstances in the past ten weeks. Luke is devastated by the loss of his friends and colleagues, and his inability to locate the killer feels like a personal failure. He and his team are experts at shielding others, but now the protectors are in need of protection.

FBI Special Agent Faith Malone is driven to succeed and confident in her ability to solve every case she's assigned. She's been put in charge of the investigation into the unprecedented attacks, and with Luke's life in danger, the stakes have never been higher. But it's hard to know how to fight back when you don't know who the enemy is.

Luke has teamed up with Faith before, but he's not convinced she's up for the job and she's not convinced he's telling her everything he knows. As more agents are targeted, Luke and Faith will have to learn to trust each other and work together to bring a killer to justice and prevent any more names from joining their fallen brothers and sisters on the Secret Service Wall of Honor.

"Lynn H. Blackburn is an amazing voice in romantic suspense--don't miss her!"--Lynette Eason, bestselling author of Danger Never Sleeps series

"Unknown Threat is a fantastic read!"--Elizabeth Goddard, award-winning author of the Uncommon Justice series

"Lynn Blackburn has created a page-turning novel with all the elements I've come to love in her books."--Cara Putman, award-winning author of Flight Risk and Imperfect Justice

Lynn H. Blackburn is the author of Beneath the Surface, In Too Deep, One Final Breath, Hidden Legacy, and Covert Justice. Her books have won the Carol Award, the Selah Award, and the Faith, Hope, and Love Reader's Choice Award. She lives in Simpsonville, South Carolina, with her true love, Brian, and their three children.