Unhallowed Ground (2015) online

Six private school students spend a night patrolling the eerie grounds of the historic Dhoultham School as part of a British Army initiative to provide rich kids with basic military training. As each hour passes they witness a series of increasingly disturbing occurrences, slamming doors, self-governing lights and ghostly apparitions. The ante is upped by two thieves who have chosen the night to conduct a heist on the school Archive: a vault of priceless historical documents. As the supernatural encounters begin to take an increasingly malevolent turn, the students realise they must escape Dhoultham before the night's end.