Maggie and Supergirl team up to save Alex in new photos Following the promo earlier this week, The CW has released the first batch of photos for the next episode of Supergirl. Check them out in the gallery below! Titled “Alex” and set to air May 1, the episode is described as follows: “Alex (Chyler Leigh) is kidnapped and the kidnapper threatens to kill her unless Supergirl (Melissa Benoist) releases a notorious criminal from prison.