"Girls Night Out" starts off with Barry, Cisco, Harry, and Ralph Dibny researching who the mysterious "Devoe" is. Felicity Smoak walks with balloons — she's in town for Iris' bachelorette party.
Felicity and Iris go upstairs where Caitlin is seen booking an airplane ticket. The latter tells Iris and Felicity she's not feeling up to going out but they convince her otherwise.
At Joe's place, Cecile is looking at her ultrasound pictures with her daughter Joanie. The doorbell rings and it's Barry, Cisco, and Harry — they're celebrating Barry's bachelor party.
Cisco sets up a screen and starts watching home videos when Ralph barges in uninvited. He persuades them to change their plans and go with him instead.
The ladies — Iris, Cecile, Caitlin, and Felicity — are out having dinner when Caitlin's seen chugging her drinks. The strange man we saw earlier in the year at Caitlin's bar approaches them and orders Caitlin to go with him. She declines and his fake eye falls out, exposing some snake-like object the protrudes from his eye.
A fight breaks out and Caitlin turns into Killer Frost, much to the surprise of the other ladies.
Ralph leads the gentlemen to one of Central City's strip clubs — where the workers know Ralph on a first-name basis. They start getting drinks and Cisco makes sure Barry has his specialized alcohol.
Iris goes to call Barry, but the bouncer at the club took all of their cellphones away.
The girls head back to STAR Labs and Killer Frost tells the group that Caitlin had planned on leaving earlier in the
Back at the club, Barry's drunk and going around telling everyone he's The Flash. Joe goes up and pulls him back to their table when a new dancer named Jasmine takes the stage. They look up to realize it's Cecile's daughter.
Elsewhere, Killer Frost is on a tear, looking for the guy that approached her earlier. We see her enter a different nightclub and approach the guy with the snake eye — he's the henchman for a lady named Amunet.
Iris, Felicity, and Cecile have followed Killer Frost to the club. Amunet takes Killer Frost to the basement, where she has someone chained up — she says the guy, who she calls Weeper, is a newfound metahuman — his tears are some new drug.
Amunet explains that with the man's powers, she needs a bodyguard because she plans on selling the tears as drugs. Killer Frost refuses and Amunet threatens t kill
Killer Frost tells the group that Caitlin had previously agreed to work with Amunet because she had some tech Caitlin wanted.
Iris tells Felicity and Cecile that they need to save Weeper from Amunet and they agree. Killer Frost decides she's going to leave Earth-1 when Iris tries to persuade her to change back into Caitlin.
Back at the strip club, Joe's speaking with Joanie — she tells him that she's not an exotic dancer, rather she's working on writing a book about the strength of women.
A dancer approaches Dibny and
Killer Frost meets Amunet in an
When Amunet switches her attention back to Caitlin, she turns around to find her gone from the scene.
Caitlin's made her way back to STAR Labs, where she's getting patched up by Iris.
After their fight at the club, all of the guys are in jail. Dibny's running his mouth saying he'll get them out while Barry gets sick from the drinking. Talking to Barry, Joe reveals he's afraid to be a new father again. Barry offers some words of encouragement.
At STAR Labs, the ladies are trying to figure out how to find out how to track Amunet. Caitlin tells them that Amunet can control a type of nickel alloy and Felicity uses that information to track that type of metal to an industrial park.
Iris, Felicity, and Cecile head out to stop Amunet from selling Weeper to a mobster — Cecile stays in the lookout van while Felicity and Iris go closer with a pair of weapons.
As Iris and Felicity are about to move in, they're stopped by some of the mobster's henchmen
The henchmen take Iris and Felicity to Amunet — but Caitlin shows up. She tells Amunet to let them go and in return, she'll come back to work for her. She turns back into Killer Frost and form an ice barrier around herself, Iris, and Felicity. Remotely, Cecile is able to turn on a magnet at the industrial park, which takes Amunet's special metal alloy weaponry.
Killer Frost forms an ice dagger and is about to stab Amunet with it, when Iris persuades her not too. The group saves Weeper, who runs off from the scene.
Barry, Cisco, and Ralph show up to STAR Labs, where the two groups talk about their nights. Killer Frost turns back into Caitlin again, who explains what she's been through the past few months.
At Joe's house, Joanie walks in and they talk. She tells him she's going to do what she
Cecile walks in with some burgers and Joanie here mom if she wants breakfast in the morning and
Iris and Caitlin are talking at STAR Labs and Iris asks Caitlin to be her Maid of Honor. Caitlin's honored for the role.
We see Weeper jump a fence in a dark alleyway. He's running away from something, and we see it's The Thinker.