In Los Alamos, New Mexico, during World War II, secrets dominate every facet of family and professional life as scientists Frank Winter and Charlie Isaacs 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 one of its members, while new security measures affect the scientists' work.

A high-profile guest shakes things up on The Hill; Frank is haunted by his past; Frank clashes with Charlie to protect his mentor.

After Babbit becomes the subject of an investigation, Frank clashes with Charlie to protect his mentor.

Frank seeks answers about a medical issue; Charlie and Helen take a trip in order to survey an off-site reactor.