The upcoming episode of "The Flash" season 4 will welcome back the Gypsy (guest star Jessica Camacho), and the timing of her return is just about right as Team Flash will need any help that they can have in order to stop Clifford DeVoe/The Thinker (Neil Sandilands) in his latest scheme. Episode 20 will also feature the reunion of Gypsy with Cisco (Carlos Valdes), and it looks like the two will have a lot to catch up on.

"The Flash" season 4 episode 20 is titled "Therefore She Is," and based on the latest promo released by The CW, Barry Allen (Grant Gustin) will be working with Gypsy to defeat The Thinker once and for all. Unfortunately, taking down DeVoe appears to be impossible at this point, considering all the meta powers that the villain has absorbed in the last few episodes. The last meta human who fell victim to DeVoe's sinister plan is Ralph Dibny/Elongated Man (Hartley Sawyer).

The Episode 20 trailer reveals that The Thinker is up to something nasty once again, and Team Flash will try to sabotage whatever he is planning to do. Together with this wife, Marlize DeVoe (Kim Engelbrecht), also known as The Mechanic, The Thinker will create a new machine that will help him go to the path of The Enlightenment. Marlize has always been loyal to her husband since the beginning, and with the help of her knowledge, The Thinker was able to build a cybernetics technology that allowed his consciousness to jump from one body to another.

Unfortunately, Marlize has no idea how evil her husband truly is, but in "The Flash" season 4 episode 20, she may begin to realize The Thinker's true motives. The trailer shows DeVoe assaulting his own wife, which is a proof that the villain has never actually cared for anything or anyone other than his ambition.

Lastly, "The Flash" season 4 episode 20 will feature the interaction between Cisco and Gypsy, as the two try to figure out their future together. There may be a lot of things happening in Central City that keeps the two of them occupied, but it wouldn't hurt if both of them have a deep conversation to settle their relationship.

"The Flash" season 4 episode 20 will air next Tuesday, May 1 at 8 p.m. ET on The CW.