[SPOILER] Returns To Star City in Arrow Midseason Finale Shocker

SPOILERS AHEAD for tonight's episode of Arrow, titled "What We Leave Behind."

Tonight on Arrow, Oliver Queen fully believed taht he had finally figured out who Prometheus was. Instead, it was revealed to be that person's son, who bound Felicity's hero-cop boyfriend, sent him out in costume, and fooled Oliver into murdering him.

"Detective Malone should not be afraid of Oliver," Amell told Green Arrow TV during the red carpet for Arrow's 100th episode party. "Detective Malone should be afraid of his connection to Felicity."

That wasn't the real shock -- at least not for Oliver -- though. The real shock was returning the the Arrowcave to find an intruder standing in front of the costume bank. As he approached the figure, she turned...

...and revealed herself as Laurel Lance, seemingly back from the dead.

"We find her in an unexpected spot in a very, very retrospectively expected time," Amell had teased in that same interview about the return of Katie Cassidy, who was cast as a series regular across all four CW/Berlanti series in the DC TV Universe.

...but is she for real? Is this just a dream, a hallucination? There's no telling yet. Expect more from producers soon.

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.

Arrow airs on Wednesday nights at 8 p.m. ET/PT on The CW. "What We Leave Behind" will debut on December 7, 2016.

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