Arrow season 3 actors will continue visiting Central City in upcoming episodes of The Flash and vice-versa.

As we know, in episode 18 Felicity and her boyfriend Ray Palmer visit Star Labs for a little help with his Atom suit.

In episode 19, Joe and Cisco will travel to Arrow's Starling City for answers about the mysterious Dr Wells, and they also meet the Black Canary.

Titled Who Is Harrison Wells, the episode will air on 21 April at 8pm on The CW.

According to the official synopsis, "Joe (Jesse L. Martin) and Cisco (Carlos Valdes) head to Starling City to continue their investigation of Dr. Wells (Tom Cavanagh). While in town, the duo enlists the help of Captain Lance (guest star Paul Blackthorne), and Cisco meets the Black Canary (guest star Katie Cassidy), who asks him for a favor."

Meanwhile, back in Central City, "Barry (Grant Gustin) races to catch a meta-human named Hannibal Bates (guest star Martin Novotny) who can transform himself into every person he touches – which includes Eddie (Rick Cosnett), Iris (Candice Patton), Caitlin (Danielle Panabaker) and even The Flash."

Wendey Stanzler directs the episode written by Ray Utarnachitt and Cortney Norris.

The official synopsis of episode 20 is also out. In the episode Barry and Caitlin will set a trap for Wells, and this will put Cisco's life in grave danger.

The episode is titled The Trap, which will air on 28 April at 8pm.

According to the synopsis, "Barry (Grant Gustin), Caitlin (Danielle Panabaker), Cisco (Carlos Valdes) and Joe (Jesse L. Martin) set a trap for Wells (Tom Cavanagh). Cisco uses himself as prey which puts him in grave danger. Meanwhile, Eddie (Rick Cosnett) makes a decision regarding Iris (Candice Patton), which leaves Joe a bit unsettled."