The Kennedy family is shaken to its core when Ted's car accident at Chappaquiddick results in the death of his female companion. Jackie returns from Greece - over the objections of Onassis - to help the Kennedys, only to find herself drawn into their attempt to save Ted's career by evading justice.

The Chappaquiddick disaster is resolved, though a permanent cloud hangs over Ted's public life and his conscience. Jackie's marriage to Onassis ends when the death of his son convinces him that she's the bearer of the "Kennedy curse". She returns with her children to live in New York, but her relationship with JFK Jr is strained as he chafes under the burden of his father's name. Ted falls deeper into alcoholism and depression when his son suffers a catastrophic illness.

By August of 1961 the Russians move troops into Berlin, though their intentions are unclear. JFK prepares for the possibility that Khrushchev may try to take the city. Bobby announces the formation of the Organized Crime Division. Chicago mobster Sam Giancana is livid about it, and blames Frank Sinatra, who had arranged a meeting between the gangster and Joe Kennedy Sr before the 1960 election.

Jack and Bobby try to convince their father that Bobby's being named Attorney General would be a major mistake. Quickly drawn into the Bay of Pigs crisis, virtually all of Jack's advisers - military and civilian - urge him to go ahead with the invasion. JFK is unsure that the plan will work, and he worries that the operation will be linked back to the US - causing major problems with Cuba's ally, the Soviet Union.