"Pretty Little Liars" season 4, episode 24 titled "A is for Answers" is the season finale installment. This action-packed episode unravels mysteries about the night Ali disappeared. Viewers are dying to know who is in the grave. Fans can watch "Pretty Little Liars" season 4 finale online via ABCFamily.com, iTunes and Amazon Instant Video.

"Pretty Little Liars" Season 4, Episode 24 - Air Date Info

Watch the finale episode on Tuesday, March 18, 2014 on ABC Family at 8 p.m. ET.

#AliTellsAll, this hashtag explains everything. Alison is ready to share her story with the Liars.

Official synopsis for "Pretty Little Liars" season 4, episode 24.

"After years of questions and mystery surrounding the night Alison DiLaurentis disappeared, her four best friends come face to face with Ali and finally learn what really happened to her that September night. Now with their newfound knowledge of Ali's long-held secrets, can Aria, Emily, Hanna and Spencer help Alison finally figure out who "A" is?"

In a sneak peek for "Pretty Little Liars" season 4, episode 24, Hanna tells Alison that they think her mom is the one who stole the game from Mona.

"We think she's A," says Hanna. Ali looks at Spencer but says nothing.

"I've never figured out the right way to tell you what you need to know. I've never been able to say the words out loud," says Ali as she is set to tell the truth about the night.

In the finale episode, many old characters return. Melissa is coming back, although it is not clear if she is coming in the present or it is a flashback scene. Also, Noel returns. Jenna and Ian appear in the promo photos.

Season 4 finale episode also has a mind-blowing Mona and Ali scene.

"Pretty Little Liars" season 5 starts with a "beloved character" in "serious danger." It is likely that the character gets hurt in the finale of season 4.