At the beginning of the current season of Arrow, Oliver Queen and Felicity chose to send Oliver's son William away to a boarding school to protect him from the looming threat of Ricardo Diaz. Now, with Diaz behind bars and Oliver's public identity as the Green Arrow helping him work with the Star City Police Department, William returns to Star City in the latest Arrow promo, but his parents are disappointed to find that he is hiding something from them.

The timing could not be worse, as members of Team Arrow investigate the actions of a recent serial killer dubbed "the Star City Slayer." Despite the team's best efforts without Oliver, it would appear the Queen's family problems may be resolved in the worst way possible, as the killer sets his sights on them.

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The hints that William is hiding something from Oliver and Felicity shouldn't be surprising, considering the lengths his father went to conceal his identity as the Green Arrow from the world and even William, himself. The flash-forwards of Season 7, which focus on William investigating the clues left behind from his estranged parents, allude to William identifying as either gay or bisexual, so this secret could be William struggling to discuss and share this important part of his identity with his parents.

The Star City Slayer portrayal seems to take the episode in a more horror movie direction, full of creepy music, creaky houses, victims tied to chairs and the search party debating the intelligence of splitting up during such circumstances.

It is unclear if the episode will take the character in a new direction or base it upon the Star City Slayer who appeared during Kevin Smith and Phil Hester's run on Green Arrow. In the comics, the Slayer was an occultist named Stanley Dover, whose obsession with obtaining ultimate power led him on a decades-long pursuit of a demonic entity called the Beast With No Name. At one point, he kidnapped and murdered young children in hopes that the sacrifice would attract the attention of the Beast. This actions brought a newly resurrected Oliver Queen into his peripheral and a failed attempt to transfer his mind into Queen's soulless body resulted in Stanley ironically being devoured by the very creature he sought to capture.

Hopefully, Team Arrow saves Oliver and his family before it's too late, although as the promo hints, their rescue mission could prove to be lethal if they're not on their guard.

The official synopsis for the episode reads:

Oliver (Stephen Amell) and Felicity (Emily Bett Rickards) are disappointed after they learn that William (guest star Jack Moore) is hiding something from them. Wanting to focus on his family, Oliver steps back from his Green Arrow duties and lets the team take over tracking down a serial killer. However, when the team becomes targets for the killer, things take a bloody turn. Gregory Smith directed the episode written by Beth Schwartz & Jill Blankenship.

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Airing Mondays at 8 p.m. ET/PT on The CW, Arrow stars Stephen Amell as Oliver Queen, David Ramsey as John Diggle, Emily Bett Rickards as Felicity Smoak, Rick Gonzalez as Wild Dog, Echo Kellum as Mr. Terrific, Juliana Harkavy as Black Canary, Colton Haynes as Arsenal, Kirk Acevedo as Diaz and Katie Cassidy as Black Siren.