Before this week's epic CW crossover, "Arrow" revealed that Evelyn Sharp -- Oliver's new recruit Artemis -- is actually working for Prometheus. It's unclear why she's thrown in with the masked killer, but next week's midseason finale appears to shed some light on this unexpected alliance.

RELATED: Arrow & Prometheus Have An Explosive Confrontation in New Photos

This new promo for "What We Leave Behind" shows Prometheus' hit list, with photos of Oliver Queen, Quentin Lance, Thea Queen and all of Team Arrow. As he begins to cross off names in an attempt to make Oliver wish he were dead, Team Arrow will discover Artemis' betrayal. "This city needs to be saved from you," Artemis tells Oliver.

PROMETHEUS MAKES A DEADLY MOVE AGAINST OLIVER AND THE TEAM — After Prometheus attacks Curtis (Echo Kellum), Oliver (Stephen Amell) realizes Prometheus knows all of Team Arrow’s secret identities and is planning to come for them one by one. Felicity (Emily Bett Rickards) and Detective Malone (guest star Tyler Ritter) discover a clue that links Prometheus to Oliver’s past. Antonio Negret directed the episode written by Wendy Mericle & Beth Schwartz (#509). Original airdate 12/7/2016.

Airing Wednesdays at 8 p.m. ET/PT on The CW, "Arrow" stars Stephen Amell, Emily Bett Rickards, David Ramsey, Willa Holland, Echo Kellum and Paul Blackthorne.