As Danny and Lexi finish tracking down the last of Farouk's black market antiquities, they begin to make plans for their future. But their plans are derailed when the Vatican is attacked by terrorists. A person from Danny's past returns, leading them on a new hunt to recover one of the greatest lost treasures of Asia, the Spirit Banner of Genghis Khan.

The search for Kate Reece takes Danny and Lexi to Vietnam, where they reunite with none other than Aiden Shaw. Lexi's fighting skills are put to the test as the team infiltrates the dangerous Black Lotus - an underground fight club - where they learn about a vicious new terrorist.

A visit with Simon in prison yields new information on the Spirit Banner's last whereabouts, sending the team to Russia.

Danny and Lexi join forces with Levchenko's gang as they journey to Mongolia. Levchenko hopes to find the Spirit Banner for himself, even with the Great Khan's horde in hot pursuit.

In search of the Spirit Banner, Simon attempts to make a deal, unaware that Lexi, Danny and Shaw are on his tail. What they uncover leads them to Hong Kong while Danny becomes increasingly concerned with Violet's control over Lexi.

With a trail of new clues, Danny, Lexi and Violet travel across a dangerous chemical wasteland in Kazakhstan to Aralsk-7, an abandoned bio-weapons facility. Meanwhile, Chuck begins his investigation about how the Vatican and the Spirit Banner are connected.

Danny enlists his estranged father, Patrick, in their quest for the Spirit Banner. Patrick leads them to a secret base in Laos, where he makes a startling admission to Lexi about the secret he's hiding from his son.

After crash-landing in the jungles of Laos, Lexi is gravely injured, leaving Danny and Patrick in a rush to find refuge. Meanwhile, Chuck uncovers new information on the relationship between the Vatican and the CIA.

The recovered scroll's translation takes Danny, Lexi, Kate and Violet to the snowy tundra of Mongolia, with deadly results.

Lexi is kidnapped after making a shocking discovery. Shaw uses an underworld contact to help him and Danny discover her location and face off against the Khan's interconnected gang of criminals.

The pieces of the Khan's end-game fall into place as Danny and Lexi must put their differences aside in order to stop the Khan and Simon before it's too late.

Realizing they've taken the Khan's bait - and putting the lives of millions in jeopardy - Danny and Lexi come face-to-face with the Khan in one final battle above Hong Kong.