There's a new duo moving into ABC Family's Ravenswood.

L.A. Complex's Brett Dier and model Elizabeth Whitson have boarded the cable network's Pretty Little Liars spinoff series, The Hollywood Reporter has learned exclusively.

Ravenswood centers on a town not far from Rosewood, Pa., that has suffered for generations under a deadly curse. Five strangers find themselves connected by the fatal curse and are charged with investigating the town's mysterious and terrible history before it's too late for everyone.

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Pretty Little Liars star Tyler Blackburn, who plays Hanna's (Ashley Benson) significant other Caleb, will leave Rosewood and topline the new series as a regular. Blackburn will be seen traveling to the new town in the Halloween hour.

Blackburn -- a Pretty Little Liars regular since 2011 -- still will be an integral part of the mothership's upcoming summer season before switching gears in October. How Blackburn's character enters into the Ravenswood equation and the future of the Caleb-Hanna relationship remains to be seen.

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Dier will play Abel, a lone wolf and old soul with a brooding intensity. There's something dangerous lurking inside him -- or he could be wounded and covering. His trust is hard won, but once you're in his inner circle, he'll never let you down.

Whitson, meanwhile, will play Olivia, Abel's twin sister and a former prom queen who has fallen from grace. She's learning who her real friends are after most everyone in her inner circle turns their backs on her. Recent events have left the once carefree and effortlessly happy Olivia questioning what's important.

They will both be introduced in Pretty Little Liars' Halloween episode.

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Marlene King, Oliver Goldstick, Joseph Dougherty and Leslie Morgenstein are on board to executive produce Ravenswood, which like Pretty Little Liars hails from Alloy Entertainment and Warner Horizon Television.

Dier, whose credits also include Bomb Girls, V and Emily Owens M.D., is repped by Gersh and Red Management. Whitson is with Sweeney Entertainment.

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