Cassian Holt and Jonah have finally built something that feels like peace. Mornings on the Ozark property, training sessions with Sig, coffee on the porch, and a life that no longer feels borrowed. Then Dr. Rhea Sato calls from St. Louis with a medical mystery that is already turning deadly.

Six people are dead after attending a biotech networking event. The symptoms are too fast, too precise, and too coordinated to be natural. Within hours, the Critical Trace team is on the move, setting up mobile command outside Helix Core, a gleaming biotech tower now caught between corporate denial, federal pressure, and the possibility of a deliberate attack.

As Rhea and CDC specialist Marcus Hale examine the evidence, Maya, Eli, Cassian, and Jonah begin to trace a pattern of deception that points beyond one laboratory and one suspect. Someone has used science as a weapon, and the next step could put an entire city in danger.

For Cassian and Jonah, the case is more than another federal emergency. It is a brutal reminder that the life they have built together can be called away at any moment. To protect it, they will have to confront an enemy who understands systems, fear, and power far too well.

Vector Burn is a thriller-forward MM romantic suspense novel in the Critical Trace Crime Files series, blending queer partnership, federal investigation, biotech conspiracy, and escalating danger.