Watch The Supergirl 3×17 “Trinity” Promo

The promo for the new episode of Supergirl has been released. This new episode is titled “Trinity” and it will air on May 7.

In this new episode, “Still reeling after learning about Lena’s (Katie McGrath) secret, Supergirl (Melissa Benoist) asks Guardian (Mehcad Brooks) for a favor that could alter his relationship with Lena forever. Meanwhile, with all three Worldkillers united, Supergirl and the team brace for an epic battle.”

Source: The CW