A plane crash in the Ural Mountains sends Tom and Nez to Russia on a covert operation to infiltrate a mysterious, top-secret military facility. Scottie enlists Mr. Solomon to find answers about her husband.

When ruthless terrorists escape from a "black site" prison in Manhattan, Tom and the Halcyon team must lock down the city and find the terrorists before disaster strikes.

Tom and Mr. Solomon go under cover on an international flight that they believe will be hijacked by a ring of ruthless thieves who steal classified material. Howard urges Tom to find proof of a conspiracy orchestrated by Scottie.

When a wealthy businessman, his wife and young son are abducted by professional kidnappers, the Halcyon team is tasked to get the family back. But with time running out, the team must make a dangerous choice. Meanwhile, Tom risks exposure to save Howard from Scottie.

Tensions escalate between Scottie and Howard forcing Tom to reach out to an unexpected ally for help. As explosive family secrets come to light, Tom races against time to learn the truth about Whitehall.

In the explosive season finale, Scottie and Howard battle for control of Halcyon and the dangerous technology tied to Whitehall. Tom clashes with Mr. Solomon as he makes a fateful choice.