Luck Be a Lady

"Luck Be a Lady" is the third episode of the fourth season of The Flash and the seventy-second episode overall. It aired on October 24, 2017.

Synopis
Barry and the team are hit by a string of bad luck and realize it is the handiwork of a new meta, Becky nicknamed Hazard, who has the ability to give others bad luck, while cashing in the benefits for herself. Meanwhile, Harry Wells returns to Earth-1 to give Wally a message from Jesse.

Trivia

 * The title is a reference to the song of the same name, featured in the musical Guys and Dolls. The song played in the episode as well, as sung by Frank Sinatra.
 * During a game of laser skirmish, Cisco yells "you have failed this city", the former catchphrase of the Arrow.
 * The breakup cube is made of Atlantean plastic, a reference to Atlantis, the home of DC superhero Aquaman.