Nia and Brainiac (Nicole Maines, Jesse Rath) try to save Supergirl (Melissa Benoist) from the Phantom Zone by traveling back to Kara's (Benoist) hometown in 2009 in the new episode "Prom Night!" During their visit to the past, Brainiac is determined to get the item they need to free their friend, but he's also worried that he inadvertently might do something to change the future. Meanwhile, an ambitious young reporter named Cat Grant (guest star Eliza Helm) senses that a major story may be about to break in Midvale.