The CW has released an official description with spoilers for the April 15 episode of Arrow. It’s called “Lost Canary” and Legends of Tomorrow’s Caity Lotz guest stars!
Here’s the write-up:
BIRDS OF PREY; CAITY LOTZ GUEST STARS — After being accused of murder and having her criminal past exposed, Laurel (Katie Cassidy) goes full Black Siren and teams up with an old criminal acquaintance, Shadow Thief (guest star Carmel Amit), to go on a crime spree around Star City. While Dinah (Juliana Harkavy) aims to bring Laurel in, Felicity (Emily Bett Rickards) refuses to give up on her friend and tries everything to get through to her, even summoning Sara Lance (guest star Caity Lotz) for help. However, Laurel rebuffs all her efforts, forcing the former friends to face off against each other. Kristin Windell directed the episode written by Jill Blankenship & Elisa Delson (#718). Original airdate 4/15/2019.