Tuesday night's Halloween episode of Pretty Little Liars will be one of the most significant in the series' history, according to the show's executive producers.

"There is a huge reveal that changes the series to where we can never turn back," executive producer Marlene King revealed to HollywoodLife recently. Pretty Little Liars is coming off the heels of another big reveal: Ezra (Ian Harding) was revealed to be 'A' in the summer finale.

After the Halloween episode, titled Grave New World, the four girls will have a "whole new plan of attack," according to executive producer Oliver Goldstick. The episode features the girls dressing up for a costume party and hoping to get to Ali (Sasha Pieterse) before 'A' can.

The big reveal in the episode will be even bigger than the Ezra as 'A' reveal, according to the producers. Goldstick admitted that they took a risk in finally revealing the identity of 'A' as Ezra.

"We knew there would be backlash," Goldstick said. "But when you look back, a lot of things will make sense; we try to make it not so out-of-the-blue. We have dropped clues. We plant things that will pay off in a awesome way!"

Meanwhile, Spencer (Troian Bellisario) will find that Ali's return will bring out her inner warrior.

"Spencer will take things into complete overdrive this year," Bellisario teased. "Spencer becomes obsessed in a new way, and she takes on unhealthy habits to take over the investigation herself. [This special is] going to open a few more interesting secrets that nobody was ever aware of."

The Halloween episode of Pretty Little Liars airs Tuesday at 8 p.m. on ABC Family.

Watch a trailer for the episode below:

Tags
Pretty little liars, Spoilers