The biggest betrayal in the Arrowverse to date has been between Lena Luthor and her estranged best friend Kara Danvers on Supergirl, and the truth behind Lena's machinations is about to come out.
The CW has released the official plot synopsis for Season 5's seventh episode, titled "Tremors," revealing Supergirl finally learns what Lena has been up to this as season as she deals with the new threat Leviathan. Coupled with this revelation is J'onn J'onnz discovering where his long-lost brother Malefic has been recently. The official synopsis from the network is below.
SOMETIMES THE PERSON YOU WOULD TAKE A BULLET FOR IS STANDING BEHIND THE TRIGGER – Supergirl (Melissa Benoist) finally learns the truth about Lena (Katie McGrath) while tangling with Leviathan. J’onn J’onnz (David Harewood) makes a discovery about his brother’s whereabouts. Andi Armaganian directed the episode written by J. Holtham & Katie Rose Rogers (#507). Original airdate 11/17/2019.
After learning Kara's secret identity from her dying brother Lex in the Season 4 finale, Lena had sworn revenge for her friend's deception. After selling CatCo, the news media company Kara has worked for all season to the nefarious Andrea Roja, Lena has secretly taken Malefic under her control using new technology. While Kara may not learn the full extent of Lena's villainy just yet, the two estranged friends are certainly on a collision course.
Airing Sundays at 9 p.m. ET/PT on The CW, Supergirl stars Melissa Benoist as Kara Danvers, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen and Chyler Leigh as Alex Danvers.