Peggy’s search for the truth about Zero Matter puts her on a collision course with her superiors as Howard Stark barnstorms in.

Peggy discovers her murder investigation has huge ramifications that can destroy her career, as well as everyone near and dear to her.

In the season finale, Charlie accidentally puts Paddy’s up as a prize for a dance marathon, which prompts the gang to enter the competition in order to save their bar.

Recent events strain Burke and Cristina’s relationship. Mark and Derek must work together when two close-knit brothers seek medical help. One of Meredith’s half sisters is admitted to the hospital.