Pretty Little Liars Halloween episode "Grave New World": Watch online live stream tonight - season 4 episode 13 [ABC Family start time]

(ABC Family)The stars of Pretty Little Liars.

The annual "Pretty Little Liars" Halloween episode will be airing tonight at 8 p.m. ET on ABC Family. Before tonight's special episode, catch up with the latest episodes of PLL on the ABC Family website here.

If you miss tonight's episode, you can watch the special Halloween episode online on the ABC Family website tomorrow.

Tonight's synopsis for the special Halloween episode titled "Grave New World" is as follows: "The ladies crash the Ravenswood Founders Day Celebration after learning that Ali may be alive; Caleb meets a kindred soul as he travels to Ravenswood to help the girls."

The episode will also introduce "Ravenswood", a spin-off to the popular show which will air immediately after the special episode. The show is set in the town of Ravenswood, which revolves around five strangers connected by a deadly curse. The episode description reads: "Caleb stays in Ravenswood to help out his new friend, Miranda, but confrontations with unfriendly locals make him rethink his decision; Remy helps Caleb and Miranda investigate strange occurrences in the town."

Before watching tonight's Halloween episode, be sure to catch up with previous "Pretty Little Liars" episodes on ABC Family, which will be airing all day today before the new episode at 8 p.m. ET. Two pilot episodes for "Ravenswood" will immediately air at 9 p.m. after the Halloween episode.

The series summer finale for "Pretty Little Liars" in August broke records as the most social TV series episode in TV history as over 1.9 million tweets were shared. The last season was also the most popular, with over 4 million viewers tuning in.