Arrow: Season 7, Episode 18

7 - 18: Lost Canary

After being accused of murder and having her criminal past exposed, Laurel goes full Black Siren and teams up with an old criminal acquaintance, Shadow Thief, to go on a crime spree around Star City. While Dinah aims to bring Laurel in, Felicity refuses to give up on her friend and tries everything to get through to her, even summoning Sara Lance for help. However, Laurel rebuffs all her efforts, forcing the former friends to face off against each other.