I Know Who You Are

"I Know Who You Are" is the twentieth episode of the third season of The Flash, and the sixty-sixth episode overall. It aired on May 2, 2017.

Synopsis
Barry and the team meet Tracy Brand, a scientist, who may be the key to stopping Savitar, along with Savitar's true identity from the future.

Unfortunately, Killer Frost is also after Tracy so Team Flash must battle their old friend, which proves to be particularly difficult for Cisco. Joe and Cecile’s relationship takes a big turn.

Trivia

 * H.R. refers to Julian as "Romeo and Juliet" after he expresses concern over Caitlin. This is a reference to the tragedy by William Shakespeare.
 * Tracy likens herself to Sarah Connor from the 1984 film The Terminator. Cisco and H.R. disagree, comparing her instead to Miles Dyson.