Frank Winter, the head of the Manhattan Project, struggles with the sacrifices he is making to help the U.S. win World War II.

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.

The arrival of a high-profile guest shakes things up; 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.