The episode opens with the closing moments of last season, when another Kryptonian rocket crashed into the outskirts of National City. Supergirl opens up the pod to reveal....a man in a red turtleneck!
The next morning, Supergirl and the Martian Manhunter fly into the DEO's new headquarters, a large skyscraper in the middle of National City. Apparently, the DEO has always had this facility, they just didn't use it last season for reasons unknown. The "man who fell to space" is still unconscious and is under monitoring by the DEO. The DEO brings in Winn to analyze the rocket's software (he knows Kryptonian now).
On the way out, Alex asks Kara if she's going to watch the launch of the Venture, a new passenger rocket ship, but Kara says that she's going on her first date with James instead. Alex notes that Kara seems overeager about the date, which means she's trying to convince herself that the date is a good idea, but Kara doesn't respond as she has to run to see Kat.
Kat wants to know what Kara wants to do as her new vocation (Kat offered Kara whatever job she wanted last season), but Kara hasn't made a decision. Kat gives her 48 hours to decide and then berates Kara's replacement a bit.
That evening, Kara superspeeds her way through several outfits before Jimmy shows up at the apartment with pizza and pot stickers for their date. At Jimmy's urging, they put on the Venture launch, but an engine quickly malfunction causes the shuttle to fall back into the atmosphere.
We then flash to Metropolis, where Clark Kent makes his big entrance...getting chewed out by Perry White on the phone. He then hears a news bulletin about the Venture's in-air troubles. Both Superman and Supergirl fly into action. Supergirl arrives first and grabs the nose of the ship, while Superman cools off the engine and then grabs the tail. Working together, the two heroes bring down the shuttle into a field and share a goofy moment together.
Kara brings Superman to the DEO, causing most of the office to immediately start fanboying. However, there seems to be a bit of bad blood between Hank and Superman, although Alex doesn't know exactly what happened between the pair. Superman checks in on the DEO's mystery guest. Per Winn's report, they still don't know who he is, but his rocket passed through "the Well of Stars", which explains why he hasn't aged. We also learn that Kryptonians age slower on Earth, which is why Superman doesn't look 12 years older than Supergirl.
Hank then tells Superman and Supergirl that the Venture was possibly sabotaged. Hank says the DEO will handle the investigation, but Superman volunteers to assist, saying he can ask some questions as Clark Kent.
Kara takes Clark to CatCo, where she's pulled aside by Kat. It seems that Kat has a major crush on Clark and quickly takes him on a private tour of the building. Alex then calls Kara to tell her that Lena Luthor (Lex's sister) had a seat on the Venture, but cancelled at the last minute, thus making her a suspect for the supposed sabotage.
We then learn that it was John Corben who sabotaged the ship, acting under orders from a Luthor (we don't know which one). He purchases a hi-tech drone and tells his employer that he's moving to "plan B".
Clark and Kara visit Lena Luthor, who says she cancelled her Venture flight because she's planning to rename LexCorp and had to make some last minute plans for the rebranding ceremony. She gives Clark a flash drive containing information on the part that exploded and asks Clark to give her a second chance.
After they leave Lena's office, Kara asks how Clark juggles being Clark Kent and Superman. Clark tells her that being Kara is just as important as being Supergirl and gives her a hug.
Alex gets Hank to tell her about "Project Emerald", the source of Hank's issues with Clark. Back when Superman was friendly with the DEO, he and Hank discovered the first batch of kryptonite together. Superman wanted the kryptonite destroyed, but Hank kept it to use against other Kryptonians. Winn walks into the office to point out that the explosion on the Venture was trying to kill one person: Lena Luthor.
At that moment, Lena hops into a helicopter and is immediately targeted by Corben's drones. Superman and Supergirl block the drones from shooting Lena, but Corben says he's sent out drones after other civilians too. Superman goes after the other drones, while Supergirl stays behind to protect Lena.
That evening, James confronts Kara at KatCo about seemingly blowing their dates off, and Kara admits she doesn't know if she still wants to be with James anymore. Kat gives her a bit of a pep talk and tells her to step out of her comfort zone and "take a dive".
The next morning, the DEO links the drones to Corben and guess that he'll go after Lena at her company's renaming ceremony. Hank then tries to talk to Superman, but he says that he can't work with the DEO as long as he has kryptonite on site.
Bombs go off at the ceremony, causing all sorts of chaos. One of the bombs takes out a retaining wall, which somehow causes the entire LexCorp headquarters to start to collapse. Supergirl manages to cobble together a fix, while Alex fights Corben. Corben manages to get the upper hand on Alex, but Lena then shoots him from behind.
Later that day, Lena thanks Clark for writing a positive story about her new company and asks Kara where her story on the attack is. That inspires Kara to tell Kat that she wants to be a reporter. Kat pulls out Kara's resume (from when Kara first interviewed with Kat) and shows her that she scribbled "reporter" down on it, because she knew that Kara had the instincts and makings of a great reporter. Kara says that Kat has a way of inspiring people and getting them to make that dive....which seems to inspire Kat into making plans of her own.
Kara finally has a chat with James and admits that she's still trying to figure out how to "be" Kara. She then tells James they would work best as friends, ending that relationship before it starts.
Hank officially hires Winn at the DEO, while Superman says that he wants to stick around National City and spend more time with Kara.
The episode ends with Corben waking up in an underground facility at Cadmus. A woman says that he gets to choose whether to live or die. Corben says he wants to live, and the woman pushes a button that starts Corben's transformation....into Metallo!