SPOILER WARNING: This article contains major spoilers for "Underneath," the latest episode of "Arrow."

Prometheus just got his hands on someone very close to the Green Arrow: his son. In "Underneath," the latest episode of "Arrow," Adrian Chase rigged a trap in the bunker that trapped Oliver and Felicity inside. While they were struggling to get out, Chase tracked down Oliver's son William -- which doesn't bode well for Oliver or William.

Throughout the episode, Oliver and Felicity struggled to find a way out of the bunker after Chase's EMP locked them inside. Unfortunately, the bunker is nigh impenetrable, and Prometheus rigged the place with booby traps to make it even harder to escape. As soon as they realized what had happened, the rest of Team Arrow -- including Dig, Curtis, Renee, Dinah and Lila -- dedicated their time to getting them out.

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During Oliver and Felicity's ordeal, Prometheus had plenty of time to track down Oliver's son. William and his mother have both been in witness protection since Season 4, when Oliver sent them away to be in hiding for their own safety. After all, Damien Darhk also discovered Oliver's secret family and threatened to use them against him.

When Chase approached William, he was dressed down in his civilian clothes. He stopped William as William was stepping off the school bus. When Chase referred to him as William, William corrected him and said his name was Matthew, which is likely his new name since he and his mother were in hiding. Nevertheless, William was intrigued by Chase and asked if Chase knew his mother. Chase corrected him, saying that he actually knew William's father -- and William's father knew his father.

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This is where the episode drew to an ominous close. Though we didn't see Prometheus kidnap William, that seems inevitable. Chase doesn't plan to kill Oliver himself, but has no qualms about hurting or killing anyone who means something to Oliver. Chase hinted that he would go after William in "Kapiushon," where he taunted Oliver with the fact that he knew about William. That grim prophecy seemed to turn into a reality by the end of "Underneath."

Starring Stephen Amell as the Emerald Archer, “Arrow” airs Wednesdays at 8 pm ET/PT on The CW. The series also stars Emily Bett Rickards, David Ramsey, John Barrowman, Willa Holland and more.