Frank is offered a life-changing opportunity. At the same time, the U.S. Army put Charlie on the hot seat.

Akley becomes vulnerable when he tries to fix Thin Man's shortcomings.

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.

An unexpected visitor arrives on the Hill.

Frank and Charlie hatch a plan.

Both Charlie and Frank face serious questions as to the future of their projects.

Helen and Charlie deal with a crisis; Abby embarks on a journey of self-discovery.

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

Frank clashes with Charlie to protect Babbit, who has become the subject of an investigation.

The arrival of a high-profile guest shakes things up. Frank is haunted by his past.

The loss of one of their own leaves the community reeling; and new security measures interfere with the work being performed by the scientists.

Frank attempts to save his team, and pays the price; at the same time, the wives get creative trying to make life on the Hill more interesting.

A drama about the clandestine race to build the world's first atomic bomb in Los Alamos, N.M., centers on a self-destructive professor who is commissioned to help lead the Manhattan Project in the series opener.