Alone (2007)

The Shutter directors' second ghost story turns inward. Pim is the survivor of a pair of conjoined twins, and when she returns to Thailand from South Korea her separated sister Ploy seems to have come too. Marsha Wattanapanich plays both, and the film rests on her. It is a sister ghost rather than a vengeful stranger, which gives it a sadder, more personal chill, and the twist reframes everything before it. Its reach abroad showed when Bollywood made its own Alone in 2015. Pick this if Shutter's guilt-driven haunting worked for you.