—What better distraction than a psychological thriller? In Acorn TV’s “The Nest,” Dan and Emily are a happily married Glasgow couple longing for the parenthood that’s eluded them — and 18-year-old Kaya enters their lives. Is her offer to act as a surrogate in exchange for helping her get on the right path an answered prayer or something less benevolent? Martin Compston (“Line of Duty”), Sophie Rundle (“Bodyguard”) and Mirren Mack lead a cast that includes Shirley Henderson ( “Bridget Jones”). Two episodes are out on Acorn TV, with weekly episodes debuting Mondays through Aug. 3.