水面之下 From Beneath (2012)

Sticky and hot from the long drive to visit a relative at their newly acquired, remote, rural farmhouse, Sam and Jason, a young couple on vacation, decide to swim in a pond they find at the end of a freshly cut path. While swimming, Jason is bitten by a strange leech-like organism. When he attempts to remove the creature, part of it rips off and crawls inside his leg. Back at the house, Sam’s sister and her family have yet to return. As time progresses, the injury on Jason’s leg worsens into a rapidly spreading infection, and strange clues begin to reveal that there may be more to their host’s absence than it previously appeared. It soon becomes a race against time to discover what happened to Sam’s sister and her family and what lies in store for Jason, faced with his physical and emotional disintegration.