Medusa (Supergirl)

"Medusa"
Supergirl episode
Promotional poster of both the episode and The CW's crossover event "Invasion!"
Episode no.	Season 2 Episode 8
Directed by	Stefan Pleszczynski
Written by	Jessica Queller & Derek Simon
Production code	T13.20158
Original air date	November 28, 2016 (2016-11-28)
Guest appearance(s)
Grant Gustin as Barry Allen / Flash Carlos Valdes as Cisco Ramon / Vibe Helen Slater as Eliza Danvers Brenda Strong as Lillian Luthor Katie McGrath as Lena Luthor
Episode chronology
← Previous "The Darkest Place" Next → "Supergirl Lives"
List of Supergirl episodes

"Medusa" is the eighth episode of the second season from The CW television series Supergirl, which aired on November 21, 2016. The episode features a minor tie-in with the Arrowverse crossover event "Invasion!"

Kara, James, Winn, Alex, Eliza and Mon-El celebrate Thanksgiving; Alex intends on coming out to Eliza, while James and Winn debate revealing the truth about Guardian. During the speech, a mysterious interdimensional portal opens over the table. The next day, J'onn intends on discovering what Cadmus wanted with Kara's blood. Kara visits Lena to discern what she knows about her mother Lillian and Cadmus; after Kara leaves, Lena invites Lillian over to inform her that a reporter is raising suspicions about her. At the bar, Hank Henshaw plants a device that unleashes smoke. Mon-El mistakes him for J'onn and follows him outside, leading to a fight that Mon-El loses; Mon-El goes back to find all the aliens inside dead.

Mon-El is placed in isolation and J'onn agrees when Alex suggests Kara remain isolated. Eliza is brought in to help figure out the toxin. The virus consumes Mon-El and he is placed in the infirmary. Eliza determines the virus is Kryptonian and Kara believes Cadmus needed her blood so Henshaw could break into the Fortress of Solitude. At the Fortress, Kelex regards her as an intruder and attacks, forcing Kara to destroy it. She discovers that Henshaw accessed the file called Medusa, a virus which Kara's father created for defense against potential invaders. Alex attempts to come out to Eliza, but Eliza already figured it out and is fully supportive. Kara reveals to J'onn how upset she is that her parents would unleash a virus on their enemies; he confides that he is turning into a White Martian, but does not want anyone else to know until Cadmus is stopped.