Spencer has been keeping a secret from her loved ones on 'Pretty Little Liars,' but it's not entirely her fault, as her memory is missing pieces from the night of the infamous sleepover where Ali went missing.

Seems, however, that someone is going to help her get those memories back -- but who?

As always, spoilers are below, so proceed with caution.

"With Spencer, there are big gaping holes in her memory which will serve as incredibly difficult realizations about what she may have done," revealed 'PLL' executive producer Oliver Goldstick. "There are revelations and realizations that she maybe had confrontations or ugly encounters that she may have blotted out and can't remember." Most likely with Ali during said sleepover.

He continued, "But there are people that are going to remind her, you better believe it! Somebody was taking notes that summer."

This clue could either point to Ezra himself -- who researched the disappearance surrounding Ali to write his true crime book -- or Ali's diary. Although it may have been difficult for Ali to have filled in her own diary while being buried alive.

"Spencer always has a big secret, but this is a big one," actress Troian Bellisario previously teased. "This is what’s so great about the show. They are unafraid to keep something like this for almost four seasons. We’re going to learn what actually happened the night Ali disappeared, and it’s going to be so fulfilling for fans who have been waiting years for it to all come together."

As the synopsis for 'Unbridled' revealed, Spencer's memories will already have returned by the penultimate episode: 4x23 so we have a feeling Spencer will be reacquainted with her past in episode 4x22, 'Cover for Me' which is scheduled to air on March 4.

'Pretty Little Liars' continues tonight (Feb. 25) at 8PM ET on ABC Family. So excited!