'The Flash' is Doing a Callback to the Big Arrowverse Crossover

In the latest sneak peek at tonight’s episode of The Flash, we learn that not only will the show cross over briefly with Season 1 of Legends of Tomorrow, but there’ll be a callback to that gangbuster “Invasion!” Arrowverse crossover event.

In “Infantino Street,” Barry is running out of time. With less than 24 hours before Iris is slated to be killed by Savitar, Team Flash realizes that they need a power source for their secret weapon. Turns out A.R.G.U.S. has the only thing powerful enough, but it’s leftover tech from the Dominators’ invasion. After Lyla refuses to let them use it, they have to hatch a plan to steal it. But because A.R.G.U.S. has power dampeners that block Barry’s super speed, they need a pro to help them carry out a legit heist. Oh, and their highest-profile prisoner, King Shark, is the A.R.G.U.S. “guard dog.”

Barry’s solution is to run through time and track down a version of Leonard Snart during his tenure aboard the Waverider on Season 1 of Legends of Tomorrow. Unfortunately, the power source is still guarded by King Shark, and the two of them have to figure out a way to steal the battery and survive a giant, superpowered humanoid shark in the process.

Check out the sneak peek here.

With only two more episodes to go this season, The Flash airs Tuesdays at 8 p.m. Eastern on The CW.