A movie on HBO about 5 years ago where a young man inherits a house, I think from his Aunt. After moving in he finds a cave or maze underneath. He also finds a diary of the past owner describing monsters and demons he has came into contact with below the home. The movie trailer shows this man seeing a silhouette of a monster outside in the dark, standing in the bushes.  He enters a tunnel in the basement of the home that leads him far away from the home when he finally exits.