'Pretty Little Liars,' the teen mystery-thriller television drama series, will be back with Season 6 episode 1 on ABC Family on Tuesday, June 2, at 8.00 pm ET.

Latin Post reports that in 'Pretty Little Liars' Season 5 finale, "A" aka Charles gives a gas mask to Mona, but she never uses that. According to Jess of EW, "A/Charles never gives a present without a reason behind it. In fact, Janel Parrish assures fans that the gas mask will play an important role when season 6 returns with the girls still trapped in the dollhouse."

Meanwhile, Parrish says that while Mona "will be treated differently because she is [Charles'] favorite," it doesn't denote that she will be off the hook. "[Mona] will ultimately still be punished," Parrish adds.

According to Spoilers Guide, the promo poster of 'Pretty Little Liars' Season 6 shows Mona wearing the gas mask, suggesting that she may be using it at some point in the series.

In the meantime, 'Pretty Little Liars' actress Sasha Pieterse spoke to Zap2it regarding the upcoming season of the show. She explained some more details regarding A, a mysterious character who has been terrorizing her as well as the Liars for years.

"She has no clue who this person is. I'm pretty sure I'm able to say that," Pieterse says, adding, "It's completely a shock to her [when she finds out Charles is A]. And so, that also brings up if Charles is somehow related to the DiLaurentis family, how come no one knew about him?"

The actress goes on to explain, "That unravels a whole other different but cool storyline actually because as much as everyone knows what's happened and the girls are trying to figure it out, they're also following their own story line and their own demons."

This raises several questions like what will the Pretty Little Liars discover about "A", what is the precise relation between "A" and the DiLaurentis family and how will the girls escape the dollhouse. To know answers to these questions, fans will have to tune on to ABC Family at 8.00 p.m. ET tonight.