The upcoming episode of CW's "The Flash" season 4 will continue the search for the remaining bus metas that threatens Central City. Episode 17, titled "Null and Annoyed," will see Barry Allen's (Grant Gustin) attempt to capture an on-the-loose meta human that uses his power to steal. The job is quite challenging for a single hero to accomplish all by himself, so The Flash will need another hero capable of taking down some metas. "The Flash" season 4 episode 17 will also feature the return of guest star Danny Trejo as Breacher.

According to the official synopsis of "The Flash" season 4 episode 17, Barry will team up with Ralph Dibny (guest star Hartley Sawyer), also known as the Elongated Man, to confront a bunch of bus metas that are causing trouble in the metropolis. It looks like the new enemy has some extraordinary power to control gravitational force as the promo trailer shows The Flash in danger of falling to his death. 

The Flash and the Elongated Man joining forces to take down all the remaining bus metas in town sound like a good idea, but in episode 17, the viewes could see tension brewing between the two as Barry will not like Ralph's lack of concern.

Ralph appears to be more mindful of the popularity that he will gain after capturing the bus metas, instead of being more concerned about the actual safety of the public.

In other news, "The Flash" season 4 episode 17 will welcome back Breacher, who was last seen in the show together with his daughter Gypsy (Jessica Camacho). This time around, Breacher will need Cisco (Carlos Valdes) on his side to do an important task. It is unknown what kind of help will Breacher need from Cisco that he could not ask his daughter to help him.

Aside from Breacher, "The Flash" season 4 episode 17 could show The Thinker (Neil Sandilands) inching closer to the bus metas as he aims to absorb their powers.

"The Flash" season 4 is currently on a hiatus following the last episode. In the previous chapter, Barry's super-speed genes were transferred by a meta human to Iris West (Candice Patton), who had taken over her husband's job as the speedster and Central City's protector. "The Flash" season 4 episode 17 will air on April 10 at 8 p.m. EST on the CW.