Set during WWII in Los Alamos, New Mexico, secrets dominate every facet of family and professional life as scientists compete to create the world's first atomic bomb.

Frank's attempt to save his team brings serious consequences. The scientists' wives find creative ways to survive life on The Hill.

The community reels after losing a member, while new security measures affect the scientists' work.

A high-profile guest shakes things up on The Hill. Frank is haunted by his past.

When Babbit's past comes back to haunt him, Frank clashes with Charlie to protect his mentor.

Frank seeks medical answers. Charlie and Helen travel to survey an off-site reactor.

Helen and Charlie must solve a crisis at the reactor. Frank and Liza help Paloma's family. Abby begins a journey of self-discovery.

Charlie and Frank both face serious questions about the future of their projects.

Charlie and Frank are forced to work together for the good of the project. When they run into a problem, Frank turns to an unconventional resource.

The Implosion group overcomes another hurdle with help from Charlie's past. An unexpected visitor to The Hill raises suspicions about Frank.

A development overseas re-invigorates the hunt for a spy on The Hill. Charlie and Abby make a sacrifice when the plan with Frank is threatened.

Akley exposes himself when he tries to fix Thin Man's shortcomings.

Frank is given a life-changing opportunity, while Charlie finds himself in the US Army's hotseat.