"Eldorado" is the series finale of Boardwalk Empire, the eighth episode of the fifth season and the 56th episode overall. It was co-written by the series creator and Executive Producer Terence Winter & Executive Producer Howard Korder and directed by Executive Producer Tim Van Patten. It first aired on October 26th, 2014.
With his holdings in Atlantic City lost, Nucky Thompson takes a swim in the ocean. Due to Nucky's manipulation of the stock market, Joseph Kennedy's business associates are nervous that repeal will not happen, and begin unloading their shares. Kennedy suspects Nucky's involvement and visits Margaret Thompson. She convinces Kennedy to short sell his own shares. Margaret meets Nucky to inform him of her success, and they share a dance but are interrupted by a realtor. Nucky returns to Atlantic City, intending to settle his affairs before leaving. He meets Eli, gives him some money, and encourages him to return to his family. He then meets Gillian in the sanitarium, telling her the most he can do is set up a trust fund for her when she is released and that he is not sure what she wants from him. Gillian is withdrawn and has been forcibly sterilized.
In New York, Luciano and Lansky gather crime bosses from New York and all around the country and form the Commission, a singular body will mediate relations between all crime organizations in the country. Luciano also tasks Bugsy with killing Narcisse, and he is publicly assassinated in front of his church. In Chicago, Capone is served a court summons when the authorities manage to obtain his ledgers. While he publicly boasts that the charges of tax evasion won't stick, Capone says goodbye to his son before heading to court, where D'Angelo is waiting for him.
In 1897, Deputy Nucky is shocked to find out that Mabel has miscarried. Eli summons Nucky home, where he sees that his father has hit his mother again. Nucky and his father fight and Nucky warns that there will be consequences if harm were to come to his mother again. After returning to Atlantic city, Nucky notices Gillian participating in a parade. The Commodore fires Nucky but offers to reinstate him as Sheriff, if he delivers Gillian to him. Nucky reluctantly approaches Gillian, telling her that the Commodore is willing to take her in, and promising that he will take care of her.
In 1931, Nucky comes across Joe Harper again. Harper reveals that his real name is Tommy Darmody, Jimmy's son and Gillian's grandson. Tommy shoots Nucky three times before being restrained by the police. As Nucky lays on the ground dying, he sees a vision of a younger version of himself swimming in the ocean and catching a coin.