- "Did Non kill you today when he had the chance? I ordered him to spare you because blood bonds us all."
- —Astra to Kara.
At Lord Technologies, Hank tries to intervene in the fight between Non and Kara but is abducted by Non. Maxwell orders the D.E.O. to leave and refuses to reveal what the Kryptonians might have been looking for; he later makes a public statement blaming the attack on corporate esponage. At D.E.O. headquarters, Hank's secret emergency protocols reveal that Alex is his designated successor. Kara asks Astra where Non took Hank, but she refuses to divulge anything. Astra emphasizes that Kara has chosen sides against her.
Kara tells James and Winn that Cat believes her to be Supergirl, a premise Cat continues to explore through various challenges to Kara's identity. Non contacts the D.E.O. while Kara is present, offering to trade Hank for Astra. Alex agrees, but is countermanded by General Lane, who has been put in charge of the D.E.O. by a presidential order. James tries to investigate at Lord Technologies; his suspicions are raised by his observations of the damage to the facility, but Maxwell orders him off the premises.
At Astra's headquarters, Non kills a mind reading alien who finds Hank impervious to his abilities. At the D.E.O., Sam interrogates Astra by torturing her with a kryptonite injection, to Kara's horror and over her strenuous objections. James tells Kara that he has no leads on what Maxwell was hiding, but Winn later confronts James, who admits that he does have a line of investigation. Winn agrees to help bypass Maxwell's security systems; James successfully infiltrates the building, but is stopped by a biometric lock and then caught by Maxwell and his security force, who beat up James and throw him out. Astra reveals Hank's supposed location, but it's a trap; Kara saves Alex and a soldier from an explosion.
Cat decides that Supergirl's energies are wasted on the pretense of being an errand girl; if Kara can't prove that she isn't Supergirl, Cat will fire her. Later, Kara thanks Cat for the opportunity to work with her and resigns, explaining that Cat's suspicions make it impossible for her to do her job. Kara then discovers James' injuries and declares she will go after Maxwell. Winn notes that she is talking like Astra, and instead needs to let him and James investigate and find another way to expose Maxwell. Kara visits Astra and asks to hear the truth; Astra reveals that Alura believed Astra's claims about the planetary crisis, and sentenced Astra on the basis of her crimes, without losing faith in her. Astra favorably likens Kara to Alura, and tells her that going through with the exchange is the only way to rescue Hank. Kara decides to do so, but General Lane threatens to stop her by force. However, he is unable to follow through when the soldiers follow the lead of their fellow whom Supergirl rescued, who refuses to act against her. The trade is made, but then Non springs an ambush; however, Astra calls off the attack, demanding that a reluctant Non honor the agreement, though it is not a truce.
At CatCo, Hank uses his shapeshifting ability to impersonate Supergirl so that Cat can see her and Kara at the same time. Cat accepts that she must have been wrong, and offers Kara her job back on the condition that she not reveal Cat's embarrassing mistake. Hank offers Kara a full-time job at the D.E.O., but she tells him that her relationships at CatCo are what humanizes her. She has an online chat with Superman, who offers her emotional support, and assistance if she ever needs it. He reiterates a Kryptonian proverb that has been a motif throughout the episode: "Blood bonds us all," referring to all Kryptonians but by extension all sapient life. James, Winn, and Kara commit to stopping Maxwell.
At Room 52 of the secret facility inside Lord Technologies, Maxwell checks on a test subject, a young blonde woman who apparently died from brain trauma. She opens her eyes, revealing them to be entirely black.
- J'onn J'onzz uses his shapeshifting ability to convince Cat that Kara is not Supergirl. In the 1997 Justice League of America pilot, he does the same to prevent Fire's suspicious friend Martin from discovering her superhero identity.
- During the last few minutes of the episode, Maxwell Lord is seen entering a room containing Jane Doe, which is marked Room 52. This is a reference to DC comic's New 52.
- Cat erroneously says that Kara is 24 years old when interrogating her about her past. It was established in the Pilot that Kara was 25 since she arrived as a thirteen-year-old girl and had lived on Earth for twelve years.
- Kara also claims during that same interview that she transferred to Midvale in the 8th grade when a later episode  establishes that she when she arrived she was in the 7th grade.
|Supergirl season 1|
|"Pilot" • "Stronger Together" • "Fight or Flight" • "Livewire" • "How Does She Do It?" • "Red Faced" • "Human For a Day" • "Hostile Takeover" • "Blood Bonds" • "Childish Things" • "Strange Visitor From Another Planet" • "Bizarro" • "For the Girl Who Has Everything" • "Truth, Justice and the American Way" • "Solitude" • "Falling" • "Manhunter" • "Worlds Finest" • "Myriad" • "Better Angels"|