'Pretty Little Liars: Original Sin' Cast on Playing Pregnant, Twins and Leaving PG Pasts (Exclusive)

The cast of 'Pretty Little Liars: Original Sin' is a bit more grown-up than the last time you saw them. Bailee Madison and Chandler Kinney open up to ET's Deidre Behar about shedding their PG pasts, playing key roles on Hallmark Channel and Disney Chanel, respectively. Bailee's character on the new HBO Max series, Imogen, is pregnant, which required the actress to wear a prosthetic baby bump and commit to looking (and sometimes feeling) the physical effects of pregnancy! Bailee tells ET how her boyfriend, parents and friends reacted to seeing her in costume, and how she felt while filming. Chandler, a 'Zombies' alum, opens up about why she felt 'vulnerable' stepping into the role of Tabby on 'Original Sin.' Meanwhile, Mallory Bechtel explains what it's really like to play twins on a television series, as she takes on the dual roles of Karen and Kelly. She even teases a theory that there could be a third sister locked in the basement. 'Pretty Little Liars: Original Sin' will debut July 28 on HBO Max with three episodes. Two new episodes will follow on Aug. 4 and 11, with the final three episodes debuting Aug. 18.