A group of talented Australian and American intelligence analysts deal with a terrorist attack on a civilian plane, as well as a shocking discovery of a mole in their team.

After his demotion, Gus and Jasmina look into who actually shot down Flight BM-24; Ethan and Kath narrow down their malware suspects to somebody within the team.

Kath, Ethan and Rudi find out that each of the malware suspects have ample motives. The unpredictable US President orders a US warship to undergo a voyage through the South China Sea.

Jasmina uncovers a secret that Australia will do anything to hide, while embarrassing audio is leaked of the American President that continues the damage between the US and Australia.

As tensions in the South China Sea escalate, Gus and Jasmina's relationship falters. Plus, the US gets ready to launch an air strike on a Chinese-claimed island.

In a race against China, the team desperately searches the South China Sea for signs of the missing US pilot. Meanwhile, the net slowly closes in on the Pine Gap mole.