'Arrow': Roy Harper & Nyssa al Ghul Help the Team in "The Thanatos Guild" Photos

The CW has released new photos for "The Thanatos Guild", the upcoming sixteenth episode of Arrow's sixth season.

The episode will serve as the next installment of Arrow's Roy Harper (Colton Haynes) return, which has seen the fan-favorite coming back under unique circumstances. As fans saw in last week's "Doppelganger", Roy was kidnapped by Ricardo Diaz (Kirk Acevedo), who wanted Roy to testify against Oliver Queen (Stephen Amell) in his trial.

Arrow 06x16 Gallery

Ultimately, Team Arrow got Roy to safety, with the help of Thea Queen (Willa Holland) suiting up as Speedy once again. But as the end of the episode proved, Roy and Thea will soon have another challenge on their hands.

The episode will see Nyssa al Ghul (Katrina Law) returning to warn Thea (Willa Holland) about a new threat - a rogue group of League of Assassins members, one of whom was spying on Thea and Roy in the episode's end.

And apparently, the arrival of that group will have a major effect on the topography of Arrow.

"In an unforgettable episode that will change Arrow forever, Katrina Law returns as the Daughter of the Demon, Nyssa Al Ghul," executive producers Wendy Mericle and Marc Guggenheim explained earlier this year. "Nyssa comes to Star City to warn of an impending danger that will threaten everything we know and love."

You can view the official synopsis for "The Thanatos Guild" below:

NYSSA AL GHUL COMES BACK TO STAR CITY WITH A DANGEROUS MESSAGE FOR THEA — Nyssa Al Ghul (guest star Katrina Law) returns to Star City to warn Thea (Willa Holland) that a group of renegade League of Assassins members are planning to attack her.

This group, led by Athena (guest star Kyra Zagorsky), is intent on finding a mysterious box that Malcolm left behind and will stop at nothing to get it. Nyssa helps Oliver (Stephen Amell) come to a life-changing realization.

Joel Novoa directed the episode written by Beth Schwartz & Ben Sokolowski (#616)

Arrow airs Thursdays at 9/8c on The CW. "The Thanatos Guild" will air on March 29th.