Felicity Smoak (Emily Bett Rickards) will come face-to-face with someone from her past she wishes she could forget in the upcoming episode of the hit The CW series "Arrow."

In "Unchained," Comicbook reports that Noah Kuttler aka the Calculator (Tom Amandes) is back. Oliver Queen (Stephen Amell) and his team will have to take him down as the villain attempts to cause chaos in Star City. Rumors posit that Noah is actually Felicity's estranged father and he has come to see his daughter. In a recent interview, executive producer Wendy Mericle shed some light on the connection between the two.

While she did not say that Noah and Felicity were father and child, the executive producer said they were somewhat related. Mericle told Entertainment Weekly that fans would have to tune in to find out how.

"We are very excited about this character. He does have a connection to Felicity. We're just really thrilled. Tom Amandes has been amazing in the role and is bringing a lot of kindness and a lot of malice to this character," she shared.

Meanwhile, the Calculator's arrival to Star City also means the return of an old friend. Roy Harper aka Arsenal (guest star Colton Haynes) will meet his former team, but not as an ally. The Calculator will reportedly lure Roy out of hiding and influence him to do his bidding. Team Arrow will have to stop him before he can do more crimes in the villain's behalf. Will Oliver be able to save him from the Calculator's power?

Roy's arrival may also mean a reunion with ex-girlfriend Thea (Willa Howard). The two parted ways when he left the city. The meeting will probably be awkward, as Thea is already in an on-off relationship with Oliver's campaign manager Parker (Alex Davis). The fact that they have to take him down will weigh heavily on Thea's mind as well. Do they still have feelings left for each other?

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