Black Weeds

Suggestions:

At the Mountains of Madness Howard Lovecraft and the Kingdom of Madness The Outsider The Dinosaur Project The Carnivore

A recently unemployed man is tasked with housesitting for his more successful friends. As he sinks into depression, he has an awkward interaction with a door-to-door salesman. Soon hallucinatory dream logic takes over as strange visitors begin to show up, invading his psyche as well as the house.