CBS

Season 6: Episode 17 - Valhalla

Valhalla: Prentiss’ struggle with terrorist Ian Doyle takes center stage as the BAU investigate a series of suspicious house fires in Washington, D.C. At first, it seems like the fires are unrelated â€" one caused by a gas leak, the other covering up a murder/suicide. But as the team uncovers a connection between the victims and a secretive international organization, Prentiss begins to realize that Doyle is the UnSub. Ultimately, she must decide whether to tell the team her dangerous secret or face Doyle alone.