The CW has released the official synopsis for "All-Star Team Up," the April 14 episode of The Flash featuring guest appearances from Arrow actors Emily Bett Rickards and Brandon Routh, along with The Walking Dead's Emily Kinney and classic The Flash actress Amanda Pays.

It's a crowded episode that promises to square off two big superheroes against a high-profile villain...so who better to direct than a veteran of Mortal Kombat: Legacy and Marvel's Agents of S.H.I.E.L.D., Joss Whedon's brother-in-law Kevin Tancharoen.

You can check out the official synopsis below.

“All Star Team Up” — (8:00-9:00 p.m. ET) (Content Rating TBD) (HDTV)

ARROW’S FELICITY SMOAK (EMILY BETT RICKARDS) AND RAY PALMER (BRANDON ROUTH) ARRIVE IN CENTRAL CITY; EMILY KINNEY (“The Walking Dead”) GUETS STARS AS BRIE LARVIN — Barry (Grant Gustin) is surprised when Felicity Smoak (guest star Emily Bett Rickards) arrives from Starling City along with her boyfriend, Ray Palmer (guest star Brandon Routh), who flies in as the Atom. They’ve come to visit S.T.A.R. Labs as Ray needs help with his suit. Their timing turns out to be fortuitous because it’s all hands on deck after a meta human named Brie Larvin (guest star Emily Kinney) unleashes hundreds of robotic bees to attack and kill her former co-workers, including Dr. Tina McGee (guest star Amanda Pays). A group dinner with Barry, Felicity, Ray, Iris (Candice Patton) and Eddie (Rick Cosnett) turns into a disaster. Kevin Tancharoen directed the episode written by Grainne Godfree & Kai Yu Wu (#118). Original airdate 4/14/2015.