He meets with Atlantic County Treasurer and political boss Nucky Thompson (Steve Buscemi) to show him his bootlegging operation.
Startled by this escalation of violence, Mickey returns to Nucky's side and provides information on the D'Alessios' operations in exchange for his life being spared.
In Season 2, Mickey joins Jimmy Darmody's crew, along with Al Capone (Stephen Graham), Charlie Luciano (Vincent Piazza) and Meyer Lansky (Anatol Yusef), and with them conspires to overthrow Nucky.
After Jimmy has successfully brokered a peace deal with Nucky while left him in charge of Atlantic City, he throws a party to celebrate.
[7] Mickey meets with the rest of Jimmy's crew at their new warehouse in Atlantic City to view the medicinal alcohol they have bought from George Remus (Glenn Fleshler).
[8] When Jimmy suddenly disappears following the murder of his wife Angela (Aleksa Palladino) by Horvitz, Mickey sells his entire share of the liquor in Philadelphia.
Mickey's hopes for a huge profit fall through, however, when Van Alden is forced to flee the state to escape a murder charge.
The word spreads that Mickey killed Horvitz, angering Richard Harrow (Jack Huston), the man who actually committed the assassination as revenge for Angela's death.
When Nucky's nephew, Willie (Ben Rosenfield), tries to charm his way into getting a crate of whiskey for a party, Mickey chastises him and throws him out.
[14] While Nucky is in Havana, Cuba trying to procure an exclusive distribution contract with Bacardi, Meyer Lansky unsuccessfully makes an attempt on his life.
When Nucky returns to Atlantic City, Mickey is running his bootlegging operations and Chalky White's former restaurant, now a burlesque club.
Nucky has Mickey go to New York to kidnap Luciano's associate Benjamin Siegel (Michael Zegen) in order to force a meeting and end the feud.
Before the meeting starts, Nucky gives Mickey the title and full ownership of his burlesque club, as well as five percent of every profit made there.