“Shady Grove” (** out of four) was a pretentious horror potboiler about a young couple (Niki McElroy and Todd Anthony) who attempt to leave their partying lifestyle behind them and go vacationing in a remote cabin in the woods and (what else) are besieged by a group of sinister forces that threaten their lives and their sanity. Few could have predicted back in 2008 when “The Strangers” came out that it would be imitated and ripped off countless times in the near-15 years since but seeing is believing. Good performances help you stay with film’s plodding place and bizarre plot twists but you’ve seen this all before and better. McElroy also co-wrote and co-produced.