In this exciting season finale, we watch the characters as they react to the threat of nuclear war, and follow Don as he settles back into work and home life after his 3 week absence. The men at the Stirling Cooper have discovered the merger with Putnam, Powell, and Lowe, courtesy of one Duck Phillips; Betty spends the episode debating on whether to share an important secret; and Peggy’s faith makes her question what it truly means to confess one’s sins.