The Flash finale title and trailer out: Barry and Oliver fight Reverse Flash, 5 spoilers on how season 1 will end

The Flash is soon approaching its season 1 finale, which will air on 19 May 2015, and fans are eager to know how the show would unfold.

Danielle Panabaker, who stars in The CW's hit series revealed the title of the finale episode on E!Online's instagram account.

The picture was captioned: "Who's ready for a behind the scenes peak on the set of The Flash?!? We are working on our season finale today!" —@dpanabaker

The episode is titled Fast Enough and is written by showrunners Greg Berlanti and Andrew Kreisberg.

The title may refer to Harrison's season long goal of getting Barry to run "fast enough" to allow him to time travel, or it may refer to Allen, travelling through time into the past and saving his mother.

Episode 17's opening scene showed us the night when Nora Allen was murdered and the epic Red vs Yellow streak fight.

But the shocking part was when the Yellow Streak took off his mask and fans were baffled to see that it was not Dr Wells (Tom Cavanah) as presumed, but was newcomer Matt Letscher. The episode showcased that when Eobard Thawne travelled back in time to kill young Barry, he was left stranded in the 21<sup>st century and took over scientist's identity so that he could build the particle accelerator sooner, in an effort to get home.

Thawne used futuristic technology that the producers describe as "genetic camouflage" to rewrite his his DNA.

"What happened to Harrison' real body and what really happened that night and all of these things are going to start coming out," executive producer Andrew Kreisberg told The Hollywood Reporter

Also, The CW has released a one-minute trailer for the rest of the season, titled The Future Revealed, giving fans a glimpse of what will happen in the rest of the episodes.

Superhero team-up

Green Arrow, Speedster and Firestorm are seen together in the latest promo, fighting the time travel bandit. Recently-leaked set photos also suggest that they're facing off the Yellow streak in the May 19th episode.

Oliver the new Ra's al Ghul

Since, the spinoff show will end a week after Arrow, the fact that Oliver Queen has been seen wearing a League of Assassins outfit, has led to speculation that he may actually end the season by taking over for Ra's al Ghul.

Remains found

Another major revelation will be Joe West and Arrow's Quentin Lance working together and are going to find the body of the original Harrison, who was killed by the time traveller.

As Joe says, "Anybody who knows about this (remains) is in a hell lot of danger."

Allen knows the truth

Episode 17 ended with the red streak realising that his mentor is the man in Yellow suit, who killed his mother. Going by the promo, the speedster vows to change the past and save his mother.

Gorilla Grodd is back

The one minute video also shows that Grodd is back, and will kidnap detective Joe West this time.

This season will undoubtedly end with a major twist involving Oliver Queen/Barry /Eobard Thawne's relationship.

And Grant Gustin recently teased that there is still more to find out that will "shock the audience" and the "biggest revelation" will come out at the season 1 end.

"There's a big twist that even surprised me. I've seen all the predictions online. No one has predicted the big twist that's coming at the end of this season."

So, do you think you know how season 1 will unfold? All will be revealed in episode 23rd.