We don't know the title of the episode yet or even have a synopsis, but the penultimate episode of The Flash season 4 will air May 15th and will feature an appearance by David Ramsey, who plays John Diggle on Arrow. But things aren't quite what they seem… and any more would be spoilers, so leave if you don't want to know.
Over on Arrow, Diggle is no longer teamed with Oliver Queen (Stephen Amell) and has taken a job with A.R.G.U.S., the government agency run by his wife, Lyla Michaels (Audrey Marie Anderson). And now thanks to Ramsey talking to EW.com, we have a bit more information on the role — or in this case roles — that he will be playing in the episode.
It seems we'll get to see Ramsey play to versions of himself, and no, we're not talking about an alternate Earth doppelgänger… though we haven't seen one of Diggle yet, have we? This involves DeVoe (Neil Sandilands) using the Elongated Man's powers to shift his body to look like Diggle and then infiltrate an A.R.G.U.S. facility to get Fallout (Ryan Alexander McDonald).
You get to see Diggle come in and tear through some A.R.G.U.S agents. It's always fun to go to Flash because Flash is all light.
So, Ramsey gets to play a bad guy for a minute. That makes him yet another actor to portray The Thinker this season.
The Flash airs Tuesdays at 8 p.m. ET on the CW. This episode airs May 15th, two days prior to the Arrow season finale.