Episodes 104 and 105 switched this season due to material of a sensitive nature during the Paris attacks. This week on Supergirl, Kara’s double identities leave her stretched thin while she juggles saving National City from a series of bombings and taking care of Cat’s son, Carter.
Kara finds a drone keeping tabs on her. She destroys it and confronts Hank about spying on her. He says it’s not his and takes the pieces for testing.
Cat wins an award for women in media, and the ceremony is in Metropolis. Cat tells Kara she can’t go because she doesn’t have anyone to watch Carter. Kara offers to do it. Cat thinks she’s doing it because she wants to be owed a favor. She approves.
Lucy and James have lunch together. She says she misses him and he leaves. He runs into Kara on his way out. He tells her that Lucy chose her career over him. The floor shakes. It’s a bomb a few streets over.
Supergirl holds up the structure of the bombed building so everyone can get out. Hank says the building is owned by a company that creates cutting edge technology. Alex says the drone following Kara had the same technology in it as the bomb. It was created by Maxwell Lord’s company.
Kara complains to Alex about Lucy. Alex tells her not to talk to James about Lucy unless she wants to end up in the friends zone.
Alex and Hank confront Max as FBI agents. He denies knowledge of the drone and bomb, saying the lab that was destroyed was one of his subsidiaries. Hank leaves Alex with Max to protect him.
James is overwhelmed by taking Cat’s place for the day. He tries to talk to Kara about Lucy, but she shuts him down.
Max asks Alex why she’s wasting her intelligence working for the government. She says she likes to help others. He says he feels the same, but doesn’t need a gun.
Security finds a bomb on level three of Max’s building. Since it’s Max’s technology, he cuts the wire that should stop it. Instead, it speeds up.
Kara picks up Carter who is obsessed with Supergirl. Carter asks if James could get Superman to introduce him to Supergirl. Alex calls Kara about the bomb. She asks Winn to keep an eye on Carter.
Supergirl takes the bomb and flies it outside city boundaries. It knocks her into the ocean. In and out of consciousness at the DEO, she thinks she sees Hank’s eyes glowing red. When she wakes, he looks normal.
The DEO figured out the man behind the bombings, Ethan Knox. He was fired from Max’s company and became unstable.
Kara goes to pick up lunch for Carter and runs into Lucy. Lucy says she’s afraid James is going to find Supergirl irresistible. She left James because he prioritized Superman over their relationship.
Alex tries to get Max to cancel the ceremony for his train, but he won’t. She asks him why he doesn’t trust the government. He says his parents were killed by a virus after the government deemed their lab safe.
Kara tells James that if it was her, she’d fight for love. She says if he’s not ready to move on, it won’t be fair to whomever comes next.
Lucy stops by James’s office. They argue, then she kisses him and leaves to catch a plane.
Winn notices that Carter is missing and realizes he must have gone looking for Supergirl at the train ceremony.
A call comes into the DEO that there’s a bomb at the airport. Kara starts flying there. James tries calling Lucy, but there’s no answer.
Max finds Carter wandering at the train station who says his parents are already on board. Max takes him on board to find them. Winn tries to get on the train, but he doesn’t have a ticket.
Winn sees Knox and calls Kara. He tells her that Carter is also on the train. Kara asks the DEO to cover the bomb at the airport while she takes the train.
Supergirl tells Max that Knox is on board. She asks Carter to help her by moving passengers to the back of the train.
James finds Lucy at the airport. Alex and Hank find the bomb. There’s no way to disarm it. Hank tells Alex to leave him there. When she does, his eyes glow and he tears the metal casing away with his hands. Alex is surprised when he exits the building. He tells her the bomb was a dud.
Supergirl approaches Knox, who has a bomb attached to his body. He says the bombings are his sick daughter’s only hope; now he can’t face her again. He tells Supergirl she can save the passengers. She cuts his car off from the rest of the train and pushes her side to a stop. Further down the track, his car explodes.
Alex examines the bomb Hank dismantled and finds a kill switch, which doesn’t add up.
Cat is upset that Carter was on the train, but he’s excited he met Supergirl. When Carter leaves for school, Kara asks Cat how she juggles it all. Cat says you learn.
As Kara is coming out of Cat’s office, she sees James kissing Lucy. On the news, Max is choked up about Knox’s death. Kara finds it suspicious and asks Winn to hack into hospital records.
Supergirl visits Max. Knox’s daughter is being treated by a doctor paid by Max. Kara says Max forced Knox to plant the bombs in exchange for saving his daughter. Max says he was trying to get information about Supergirl, measuring her agility, strength, speed, and weaknesses. He says on the last test, she obviously loved someone on the train, since she chose to rescue the least amount of people, compared to the airport. That person is a clue to who she really is. She tells him she’ll watch him.