In 1956, highly decorated military engineer Major Leo Carmichael is tasked with supervising construction of the British atomic test towers at Maralinga, in the South Australian desert.

The arrival of a new woman at the camp has Leo immediately suspicious, as Cranky questions his purpose following an encounter with an Aboriginal family.

In Adelaide, Leo sidesteps ASIO and receives an offer from Attorney General Wilcox that he cannot refuse. Back at Maralinga, Eva questions Quentin about his weather reports.

When Leo arrives back at Maralinga with Wilcox and members of the press, he must keep them away from the unexpected visitors hiding in the camp's kitchen.

When Carmen's friends, Molly, Lydia and Yvonne, are attacked by an ASIO operative, they show up at Maralinga hospital and confront Leo about the incident and question how it is that ASIO knew where to find them.

Leo and Corinne decide who to trust, while Eva struggles with her abductor and Cranky tells Dalgleish that he wants to stay in the desert.