The time has come for Felicity (Emily Bett Rickards) to learn the truth about Oliver's (Stephen Amell) son in the upcoming episode of The CW series "Arrow."

In "Taken," the promo shows Darhk (guest star Neal McDonough) breaking a cozy tête-à-tête between the couple by announcing a horrifying news. He will tell Oliver that he has kidnapped William (Jack Moore). When Felicity asks her fiancé whom the villain is talking about, Oliver finally admits that it is his son. Unable to believe what she just heard, Felicity stares dumbfounded at Oliver and looking quite pitiful in her wheelchair.

Last episode was a good one for the engaged couple, as they were finally able to celebrate their engagement. Unfortunately, the whole thing ended in a flat note when Darhk was seen leading Oliver's son by the hand and telling his own daughter that the boy would be staying with them for a while. William is Oliver's child with former flame Samantha (Anna Hopkins). The green vigilante learned about his existence when they went to Central City in the crossover with "The Flash."

When Thea (Willa Holland) discovered the truth about her brother, she advised him that it would be best to keep the child a secret, especially to Felicity. Oliver agreed with her, knowing that the revelation would do more harm than good in his relationship with his fiancée. Little did he know that Darhk would spill the beans about his secret son. In the upcoming episode, Oliver will deal with Felicity's reaction and his own fear about his son's safety.

To track down where Darhk has been keeping William, Oliver will ask the help of Vixen (guest star Megalyn E.K.). According to the synopsis from ComicBook, she is Oliver's old friend and her power lies in her magical ability to "summon animal powers." Vixen will be Oliver's trump card in his fight with the villain.

"Arrow" season 4 airs Wednesdays at 8 p.m. EST on The CW.