When night falls in Ennis, Alaska, the eight men who operate the Tsalal Arctic Research Station vanish without a trace; to solve the case, detectives Liz Danvers and Evangeline Navarro will have to confront the darkness they carry in themselves.
As the truth about Tsalal and Annie begins to unfold, Danvers and Navarro each confront the demons from their past.
After Navarro rescues Leah from a volatile Silver Sky protest, Danvers gets a warning against pursuing the Tsalal case any further.
Julia is struggling with mental health problems again; Navarro takes her to a clinic.
While Hank leads the search for Clark, Prior asks Danvers about the murder-suicide case that drove a wedge between her and Navarro; Navarro and Danvers seek out a local hairdresser for insight on Annie.
As Danvers and Prior set out to learn more about Tsalal, and find an unlikely location for the physical evidence, Capt. Connelly threatens to move the case to Anchorage; Navarro and Danvers separately find a connection.
When researchers suddenly disappear, Liz Danvers orders a search but tempers expectations of finding the men; Navarro tries to convince a skeptical Danvers that the men's disappearance is connected to the murder of local activist Annie Kowtok.