The Flash Season 3 premieres Tuesday night, and we already know that things are going to be shaken up in a big way thanks to Barry's (Grant Gustin) decision to go back in time and stop his mom from being murdered at the end of Season 2.

Barry's time-meddling will undoubtedly have major consequences, including potentially confusing fans with overlapping timelines. You don't need your glass window or pen just yet though because we've put together a Season 3 primer to tell you everything you need to know before Barry suits back up.

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The Flashpoint of it All

Episode 1 is titled "Flashpoint," named for the famous Flash comic-book storyline, The Flashpoint Paradox, where Barry went back in time to save his mom and almost caused the entire DC universe to collapse. We already broke down the major plot points of the comic book here, but sine the CW DC Universe doesn't have a Batman to kill and Superman is still in a completely different dimension on Supergirl, Flashpoint is more of an ode to the comic-book run rather than a direct interpretation.

"The Flashpoint paradox is a phenomenal comic book," executive producer Aaron Helbing tells TVGuide.com "With 'Flashpoint,' there will still be certain homages and certain odes, but I don't feel like we're beholden to the comic book. It's so massive in scope, you can't do it. We have to take everything that we can and we put it in The Flash TV show blender and mix it together."

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The Big Bads

There will be two big bad villains this season on The Flash, and together they will be a force to be reckoned with like never before for Team Flash.

Dr. Alchemy: Dr. Alchemy will be introduced first in Season 3. In the comic-books, he has a Dr. Jekyll and Mr. Hyde like-complex due to his multiple personality disorder. He uses his chemistry skills to create "elemental weapons," including bulletproof silicon. Once Dr. Alchemy earns possession of the Philosopher's Stone, he's able to transmute one element into another. In terms of The Flash, they'll have another villain that can compete with STAR Labs team's scientific prowess. The official casting for Dr. Alchemy hasn't been announced yet, but he is being voiced by Tobin Bell at the top of the season.

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Savitar: Another speedster! Dr. Alchemy will team up with Savitar, who in the comic-books was a former fighter pilot who also gained his speed powers from a lightening strike. Savitar has dedicated his post-lightening strike life to learning how to be faster and has managed to develop powers that none of the speedsters we've seen on the The Flash use before, like forcefields and being able to lend his speed to other objects and people. The one thing he wants most is more access to the speed force though.

So together, Alchemy and Savitar are a mad scientist and a man thirsty for knowledge. Helbing also teases that these two will be an incredibly difficult duo for the team to defeat.

"I don't think the Flash or Barry Allen or the team, have come up against villains quite like Dr. Alchemy and Savitar. Savitar is going to be, I would say, Barry's most formidable opponent — especially with Dr. Alchemy. They are two big bads. It's double the trouble," he says.

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New Faces

The Flash has some fresh blood joining the team, or at least entering the STAR Labs orbit this season. The most notable, of course, is Harry Potter alum Tom Felton who will be playing Julian Dorn.

Tom Felton, <em>The Flash</em>Tom Felton, The Flash

Dorn is a fellow CSI with Barry at the Star City Police Department, and he's immediately suspicious that there's more to Barry than his "nice guy temperament." It just remains to be seen whether Dorn will eventually became another key member of Team Flash or if he'll turn into one of Barry's enemies.

Awkward alum Ashley Rickards will also be joining the show this season for a short stint as Rosalind "Rosa" Dillion, aka The Top. She and her accomplice Mirror Master (Grey Damon) will be an evil duo who also combine their powers to confound Barry.

The Musical Is Coming

The executive producers of the CW DC universe announced in August that The Flash and Supergirl will have a special musical crossover episode to make use of both shows' tremendously talented casts. Jesse L. Martin already showed off his singing skills in Season 2, but Grant Gustin is a Glee alum, Carlos Valdes is a Star Kid with Broadway credits and Keiynan Lonsdale is a classically trained dancer.

The musical will consist mostly of already existing songs but executive producer Greg Berlanti said he hopes to have at least one original song per episode of the crossover.

What are you most excited for in The Flash Season 3?

(Full disclosure: TVGuide.com is owned by CBS, one of the CW's parent companies)