Two 'Flash' heroes for two Earths

Brian Truitt | USA TODAY

Show Caption Hide Caption Exclusive clip: A Flash/Firestorm teamup The Flash (Grant Gustin) and Firestorm (Robbie Amell) team up to take on Captain Cold (Wentworth Miller) and Heatwave (Dominic Purcell) in an exclusive clip from the season premiere of The CW's "The Flash."

Two Flashes are better than one, especially when dealing with a crisis on multiple Earths.

Not only does CW’s The Flashadd another heroic comic-book speedster in its Tuesday's second-season premiere (8 ET/PT) — Jay Garrick, played by Teddy Sears — but it also introduces the concept of a Multiverse, composed of an infinite number of Earths that occupy the same space with mirror versions of the same people who exist in a different dimension.

Confused yet? Don’t worry, says executive producer Andrew Kreisberg. Keep calm and think Back to the Future. “We do what they do: We have a very erudite professor take out a magic marker and go to a chalkboard and show people what it means.”

Echoing that film's Doc Brown, Professor Stein (Victor Garber) explains to Earth-1 superhero Barry Allen (Grant Gustin) and his S.T.A.R. Labs team the concept of other worlds when Jay, Earth-2’s Flash, arrives and warns of an evil racer named Zoom. Barry saved Central City from the “singularity,” a wormhole that threatened everyone in town in May's finale, one of several portals that opened allowing Jay and others to cross over — and a way for Zoom to rule another Earth.

“Some of the villains from Earth-2 turn out to be the doppelgangers of good people that we know on Earth-1, so that creates its own set of complications,” Kreisberg says.

The possibility of another version of Barry has probably crossed his mind, and “Grant is wondering about who Barry is over there,” Gustin says with a laugh. “As of now, he has not showed up.”

The Barry Flash fans got to know last year is much more in hero mode and a bit of a strong silent type, Gustin says. His mentor Harrison Wells (Tom Cavanagh) turned out to be a man known as the Reverse-Flash from the future who killed his mother, so he’s a little reluctant to trust Jay, a grizzled veteran who’s been a Flash for a lot longer than he.

By next week'sepisode, they’ve formed a relationship “where Barry gets to learn some tricks of the trade he didn’t know were possible,” says Sears, who says he will play a major role on the show all season.

Theseason's early episodes are devoted to the Multiverse, and just as it explored the concept of time travel last year, Kreisberg says the goal this time is to have another idea that “energizes true comic-book fans but is not so dense and insular that new people can’t come to it.”

Starting with the massively dangerous Atom Smasher (Adam Copeland), a wave of Earth-2 villains will make their way to Earth-1 throughout the season, including Sand Demon and a female Doctor Light. Gustin teases there’s even an alternate-world Wells that Barry sees walking around. “He just has to move past that this isn’t the same guy.”

In the Multiverse, “you don’t know who’s going to drop in,” says Sears, adding that Earth-2 is fairly similar, “from the look of the people and cities to the technologies they perfected.”

But keeping the show fresh means unleashing a bigger threat, and compared to the antagonistic likes of Gorilla Grodd, Captain Cold and Heatwave, Zoom is the absolute worst of the worst.

“We describe Zoom as a speed monster. He is like a demon — his costume feels less like a suit and more like the skin of a devil,” Kreisberg says of the character, who's voiced by Tony Todd. “I didn’t think anything was scarier than the Reverse-Flash, but we’re actually going to give kids nightmares. Good nightmares, of course.”