What is the title of the episode set on Sigma Iotia II, a planet modeled after 1920s gangsters?

The Star Trek episode set on Sigma Iotia II and modeled on 1920s gangsters is “A Piece of the Action.”

The episode is the 17th installment of The Original Series’ second season and first aired on January 12, 1968. The USS Enterprise visits Sigma Iotia II after learning that the earlier survey ship Horizon vanished there about a century before. The planet’s inhabitants have copied an Earth book about organized crime, turning its descriptions of 1920s Chicago into the foundation of their society.

Captain Kirk, Spock, and Dr. McCoy encounter rival gang bosses, Tommy guns, drive-by shootings, flashy suits, and underworld slang. Bela Oxmyx and Jojo Krako compete for control, while the Enterprise crew tries to resolve the crisis without worsening the contamination caused by the Horizon’s visit.

The episode is remembered for its comic tone and for introducing the fictional card game Fizzbin, which Kirk invents to distract guards. It is easy to confuse the title with other culture-focused episodes, but Sigma Iotia II and its gangster imitation are uniquely tied to “A Piece of the Action.”