After accidentally discovering the top-secret headquarters of Team Arrow, Palmer Tech's tech whiz Curtis Holt will have a regular presence when "Arrow" returns to The CW in season 5.

TVLine announced that actor Echo Kellum has been promoted as a series regular in "Arrow" season 5. His character was first introduced in the series in episode 2 as the tech genius who assists Palmer Tech CEO Felicity Smoak (Emily Bett Rickards).

Fans loved seeing the comedic banter between Holt and Felicity, especially during intense moments inside the Palmer Tech labs.

Kellum's character will eventually transform to become Mister Terrific, who could share his expertise with the Team Arrow to stop crimes in Star City. The character could also fill in the spot on the team that will be left open after the rumored death of Katie Cassidy's Laurel Lance/Black Canary in an upcoming episode of season 4.

The network has yet to announce the official premiere date of "Arrow" season 5.

Meanwhile, the next episode, titled "Eleven-Fifty-Nine," will center on Oliver (Stephen Amell) and Diggle's (David Ramsey) actions to stop Damien Darhk (guest star Neal McDonough) from getting out of prison.

The official synopsis for the episode reads:

"Oliver and Diggle learn that Merlyn (John Barrowman) is going to try to break Darhk out of prison. Meanwhile, Laurel gets a surprising offer and Felicity has a heart-to-heart talk with Curtis."

In a report from IGN, executive producer Marc Guggenheim teased that something big will happen in the upcoming episode.

"This is the episode where you find out who's in the grave," Guggenheim said.

This could mean that the mysterious identity of the person that Oliver will mourn at the end of the season will be revealed in the upcoming episode, airing on Wednesday, April 6.