When a series of corpses with ties to Booth's former Army unit appear around D.C., Booth must dive into his past to find the killer before the killer finds Booth. Meanwhile, Brennan's father, Max, hides a serious medical procedure from Brennan, leaving her to grapple with her father's trust and mortality, as well as her family being in danger.

With Kovac still at large, the team searches for evidence to track him down. After Brennan experiences a setback, the rest of the team must figure out how to find Kovac without her, putting everything she has ever taught them to the test. When all signs point to Kovac having outside help, as well as a hideout, Booth and Brennan go searching for him.