Barry (Grant Gustin) seeks help from the speed force in the upcoming episode of "The Flash" season 3.

Titled "Into the Speed Force," next week's episode will see Barry turn to the speed force out of desperation. According to the official synopsis, Barry is determined to stop Savitar and rescue his friends. To find answers, the Scarlet Speedster heads into the speed force where he meets familiar faces. Meanwhile, H.R. (Tom Cavanagh) gives Jesse (guest star Violett Beane) some advice on what her next move should be.

The CW has released promo stills for the episode and it hints at the return of familiar faces. The photos suggest that Barry will get a chance to talk to Eddie Thawne (Rick Cosnett), Leonard Snart aka Captain Cold (Wentworth Miller), Jay Garrick (Teddy Sears) and Ronnie Raymond (Robbie Amell). The last image shows an unconscious Barry lying on the floor while Ronnie looks at him.

In other news, "The Flash" and "Supergirl" are staging another crossover episode later this month. The two heroes will be facing the villainous Music Meister (guest star Darren Criss) in a special musical episode. According to executive producer Andrew Kreisberg, the musical crossover has actually been years in the making.

"We've always talked about doing it, from the very beginning, more in a joking way," he told Entertainment Weekly.

Also present during the interview was "Supergirl" lead star Melissa Benoist, who said she's excited to reunite with her "Glee" co-star Criss.

"I could not be happier that he's here," the actress gushed. "He's killing this role. He's bringing such a fun energy, the way he did on 'Glee' as well."

Aside from covers, the episode will also feature original songs such as "Runnin' Home to You" from Oscar-winning songwriting duo Benj Pasek and Justin Paul ("La La Land") and "Super Friend," which was co-written by Rachel Bloom.

The third season of "The Flash" airs every Tuesday night at 8 p.m. EST on The CW.