Barbara Kean and Tabitha Galavan set up the club together, which became a success. Barbara's acquaintance Oswald Cobblepot turned up at the bar with Tabitha's former business partner and lover Butch Gilzean to talk about a proposition Oswald presented in which he would provide protection to the club, however Barbara turned it down. Oswald then asked the pair of them to put out the word that he would pay a million dollars for Fish Mooney: Alive or Dead.
Later on, a mobster named Boris and his two underlings arrived at the bar, saying that the nightclub is on their territory. Although Boris hits Barbara, she initially feigns distress before letting out an insane laugh. Tabitha murders the two underlings with a knife, and Barbara brutally beats Boris. Believing Oswald sent them, he arrives with Butch and denies any involvement. They deduce Butch was responsible as he hoped the threat of the men would sent Tabitha back to him. Frustrated, Oswald ended the Boris' life with a bullet to the head.
The following day Barbara's former fiancé Jim Gordon arrives at the bar to ask about the location of Selina Kyle. After trying to play mind games with Jim, Barbara eventually points him in the location of an old bank.
Hypnotist Jervis Tetch became employed at the nightclub and carried out his own show which involved his skills in hypnotism which he demonstrated on a doctor. Barbara was impressed with the act, and the following evening got Tetch to try it on her. He got Barbara to fall madly in love with him, but upon rejecting her advances she held a glass at his throat, which prompted Tabitha to stop her causing further harm, much to Tetch's amusement. Gordon arrived at the bar to meet Tetch (who was his client) to demand why Tetch's sister Alice doesn't want to see him. Tetch lured Gordon onto the roof and put him under a hypnotic state and made an attempt to force Gordon to commit suicide, but this was scuppered by the arrival of Alice who shot at her brother and forced him to flee.
- Barbara Kean (co-owner; formerly)
- Tabitha Galavan (co-owner; formerly)
- Oswald Cobblepot (land owner; formerly)
- Jervis Tetch (hypnotist; formerly)
- The name of the club is most likely a reference to the comic book Gotham City Sirens which focuses on the titular team of Batman villainesses including Catwoman, Poison Ivy and Harley Quinn.