As CW's The Flash gears up for its fourth season finale, a new synopsis is teasing the addition of a "surprising ally" in the final battle against Clifford DeVoe/The Thinker.

You can read the synopsis below.

RELATED: The Flash: The Thinker's Plan for Enlightenment Explained

THE FLASH

“We Are The Flash”— (8:00-9:00 p.m. ET) (Content Rating TBD) (HDTV)

SEASON FINALE — Team Flash gets help from a surprising ally in their battle against DeVoe (Neil Sandilands). David McWhirter directed the episode written by Todd Helbing & Eric Wallace (#423). Original airdate 5/22/2018.

Although it isn't entirely clear who will come to the aid of Team Flash, Marlize DeVoe/The Mechanic did turn on her husband at the end of last week's episode, "Therefore She Is." Given her inside knowledge of DeVoe's plan, she would make a very valuable ally in the battle.

However, the new ally may also have some relation to the upcoming episode "Harry and the Harrisons," which promises to bring back Katee Sackhoff as Amunet Black, or to the mysterious female speedster that has been popping up in the show this season.

RELATED: The Flash Finally Reveals What Barry (Oddly) Listens to While He Runs

Airing Tuesdays at 8 p.m. ET/PT on The CW, The Flash stars Grant Gustin as Barry Allen, Carlos Valdes as Cisco Ramon, Danielle Panabaker as Caitlin Snow, Candice Patton as Iris West, Jesse L. Martin as Joe West, and Tom Cavanagh as Harry Wells, with guest appearances from Keiynan Lonsdale as Wally West and Hartley Sawyer as the Elongated Man.