Alex (Troian Bellisario) and Mary Drake (Andrea Parker) are a mother-and-daughter duo who appear in the later seasons of Pretty Little Liars, and their fates at the end of the show are intertwined. Pretty Little Liars is a mystery teen drama series based on Sara Shepard's novels. First premiering in 2010, the show ran for seven seasons and led to three spin-offs — Ravenswood, Pretty Little Liars: The Perfectionists, and Pretty Little Liars: Original Sin — though, Ravenswood and Pretty Little Liars: The Perfectionists were canceled after only one season each. The original series follows five friends whose secrets are threatened to be revealed by a mysterious "A" from their past.

https://screenrant.com/alex-mary-drake-pretty-little-liars-fate-explained/