The CW has released a very short official description for the March 15 episode of Arrow. The title of the episode is “Checkmate” and you can find the write-up below.
OLIVER SEEKS THE TRUTH — Oliver (Stephen Amell) gets closer to the truth about Prometheus. Meanwhile, Helix refuses to continue helping Felicity (Emily Bett Rickards) until she does a favor for them. Ken Shane directed the episode written by Beth Schwartz & Sarah Tarkoff (#516). Original airdate 3/15/2017.