NEW YORK (AP) — Sundance Channel, best known for its documentaries and other unscripted fare, is about to present a deliciously suspenseful spy thriller that signals a new initiative for the network: more drama.

“Restless,” a two-part miniseries that begins Friday at 9 p.m. EST, would be an attention-getter if for no other reason than its blue-chip cast. Here’s delectable Hayley Atwell (“Cassandra’s Dream,” ”Captain America: The First Avenger”) along with veteran thesps Michael Gambon and Charlotte Rampling, as well as Rufus Sewell (“The Pillars of the Earth”), who’s the very definition of a dashing leading man. Plus Michelle Dockery, whose return next month as Lady Mary Crawley is eagerly awaited by all “Downton Abbey” fans.