Based on the “creepypasta” short story Hidden Door by Charlotte Bywater, season four follows newlyweds Jillian and Tom, who have each brought secrets into their marriage. When they discover a strange door in their basement, those secrets start to threaten their relationship — and their lives.
An unsettling discovery prompts Jillian and Tom to suspect their home is haunted by past secrets.
After witnessing a murder, Jillian digs into secrets from her past; Tom realizes he's in danger.
A terrified Jillian and Tom reveal their secrets and try to overcome the devastating consequences.
As Jillian's old friend relentlessly hunts Tom, she teams up with a neighbor to try and save him.
Ian makes a grand gesture that threatens to drive Jillian and Tom apart forever.