Wentworth Miller as Captain Cold
Barry (Grant Gustin) and Captain Cold (Wentworth Miller) need to face off against King Shark to steal an alien power source in Season 3, episode 22 of “The Flash.” The CW

Barry (Grant Gustin) needs Captain Cold’s (Wentworth Miller) help in next week’s Season 3, episode 22 of “The Flash.”

In the trailer for the episode, Barry seemingly scoops Captain Cold, a.k.a. Leonard Snart, out from an earlier timeline and brings him to the present. “I need your help,” Barry tells Captain Cold in the preview clip. “We need to steal an alien power source.”

Because larceny is his thing, the cold gun-wielding character agrees to help the Scarlet Speedster, saying: “The Flash, a thief. It’s my kind of mission.”

READ: Grant Gustin, Tom Felton reveal they campaigned for a Barry-Julian romance on “The Flash”

In a sizzle reel teasing the final episodes of “The Flash” Season 3, Captain Cold gives Barry a rough tutorial on robbery. “There are only four rules you need to remember. Make the plan, execute the plan, expect the plan to get off the rail … Throw away the plan,” Captain Cold tells Barry in the video.

Interestingly, the duo’s plan actually gets off the rail when they find out that King Shark is securing the alien power source at A.R.G.U.S. “I can’t believe they turned King Shark into a guard dog,” Barry tells Captain Cold in the trailer.

At the end of this week’s Season 3, episode 21, H.R. (Tom Cavanagh) and Tracy (Anne Dudek) introduced the Speed Force bazooka to the rest of the team. Although the weapon is ready to use, Tracy revealed that it needs 3.86 terajoules of energy in order “to generate enough power to magnetize Savitar’s radial field and keep him in a state of perpetual stasis inside the speed force.”

As Cisco (Carlos Valdes) pointed out in the episode, 3.86 terajoules is “more than the energy in the sun.” Apparently, the alien power source, which seemingly belonged to the Dominators, can provide that energy. And with only 24 hours left until Savitar kills Iris (Candice Patton), Barry is left with no other choice but to steal the said power source from A.R.G.U.S.

Captain Cold was last seen on “The Flash” in Season 3, episode 16, in which Barry meets a version of the criminal-turned-Legend in the Speed Force. Prior to that, Captain Cold appeared as a hologram which Team Flash used to defeat Mirror Master (Grey Damon) and Top (Ashley Rickards) in Season 3, episode 4.

Meanwhile, before his surprise appearance at the end of last episode, King Shark was last seen in Season 2, episode 15. In the installment, King Shark faked his death to get his guards to deactivate the laser grid over his aquarium at A.R.G.U.S., allowing him to escape. He tracked the Flash to the West’s residence and knocked him down. But the man-shark was forced to flee as A.R.G.U.S. troops arrived in the scene.

Later in the episode, Team Flash and A.R.G.U.S. planned a trap using a Flash dummy mimicking an electrical frequency that King Shark honed in on. King Shark took the bait, but the tranquilizers hidden inside did not sedate him. But the Scarlet Speedster was able to lure him out to the ocean and defeat him by electrifying the water, subduing him. A.R.G.U.S. took him into custody once again. But this time, Lyla Diggle (Audrey Marie Anderson), the new director of A.R.G.U.S., vowed to study King Shark and find out how he came to be, hoping to cure him.

“The Flash” Season 3, episode 22, titled “Infantino Street” airs on Tuesday, May 16 at 8 p.m. EDT on The CW.