...searching for the Omegahedron (a Kryptonian power source lost on Earth), Kara creates the identity of Clark Kent's (aka Superman's) cousin, Linda Lee to become a student at Midvale School where she's given a dorm room with Lois Lane's younger sister, Lucy.
Meanwhile, evil sorceress Selina (who now posesesses the Omegahedron without knowing its' full capabilities) sends an invisible creature to destroy Kara after the teenager interferes with the sorceress' attempt to seduce young gardner Ethan...
The creature "seen" in this battle in the comic (and in the French poster at the top of this post) is never shown clearly in the movie.
It reappears in the finale of the film, but not the comic, which features Supergirl battling a different monster!The saga continues, tomorrow, back at our "sister" blog, Heroines!
Extra: Here's a scan of the original art for page 29.
A lot sharper and clearer than the printed page.