'PLL' Finale Watch: Who Is A.D.?

For seven seasons, Pretty Little Liars viewers have followed the yellow brick road that will hopefully lead to revealing the identity of "A.D." With a plethora of mysterious characters, one suspect who started the story may likely be the one to finish it.

With more curveballs than one can count, the Marlene King drama has insinuated that twin girls who share a connection with Alison (Sasha Pieterse) are the key to the mystery. While the series has already featured a twin reveal between Mary Drake and Jessica DiLaurentis (Andrea Parker), there have been hints that the sisters weren’t the only Rosewood twins — and that Spencer Hastings (Troian Bellisario) herself could have a twin she never knew of.

Ahead of Tuesday's Pretty Little Liars series finale, we propose a theory: What if the mysterious A.D. was none other than Spencer’s secret twin? Out of the four girls, Spencer has suffered the most from A.D.’s vendettas and shares the most connections to Alison after learning that Jason (Drew Van Acker) is her half-brother who was the result of her father’s affair with Jessica, with Alison's aunt, Mary, her biological mother. From there, Spencer’s complicated family tree with Alison has proven to be an important factor in the show's central mystery.

Read the rest of this article at The Hollywood Reporter.

Pretty Little Liars stars Troian Bellisario, Ashley Benson, and Lucy Hale.