Set in Humboldt County, California, Jim is a Bigfoot believer whose idea of a romantic getaway is to head deep into Six Rivers National Forest in Northern California, video camera in tow, trying to shoot his own Bigfoot footage at the site of the Patterson–Gimlin film. That 1967 fragment of footage purporting to show a Sasquatch striding along a dry sandbar beside Bluff Creek became a key artifact in the cryptozoology community and Jim dreams of nothing more than setting foot on the actual location where it was shot. His long-suffering girlfriend Kelly agrees to tag along for the ride, despite the fact that she thinks Bigfoot has about as much chance of being real as leprechauns. The two stop off first in Willow Creek, the Bigfoot capital of the world and home to an annual Bigfoot festival where various locals talk to Jim's camera, warning them to keep out of the woods, singing ballads about Bigfoot, and generally enjoying their 15 minutes in the spotlight while Jim and Kelly have a blast, cracking wise amidst all the touristy Bigfoot kitsch on display. At a restaurant, they notice a missing woman on a poster on the wall and make fun of it before dismissing it as an everyday occurrence. When they strap on packs and head into the forest via a two-hour drive down a dirt road, they start to feel like they might be in over their heads, especially Kelly. Jim, as he approaches what he considers hallowed ground, is very excited. That night they are awakened by mysterious sounds echoing through the woods, and whooping vocalizations that might be Bigfoot, but that might also be locals pranking them. The noises grow closer and less human-like and their imagination begins to wander when the noises become surreal and hits their tent. They become spooked and decide to leave the site at dawn. Jim discovers a gray, bloody strand of hair he believes may be evidence of Bigfoot's existence. They wander in circles through the thick woods while hearing the same noises they heard the night before. They become frustrated and get lost by a river bank very similar to the river bank in the Patterson-Gimlin footage they sought to find the whole trip. A whooping, angry noise rustles the bushes behind Kelly scaring her into running. As night grows in, they are confused and lost in the dark when Jim and Kelly encounter an overweight, naked woman bearing a strong resemblance to the missing woman on the poster. An unseen creature attacks them, killing Jim and moving on to Kelly whose cries for help are heard in the distance. Her fate is ultimately unknown, but implied she is taken as a "forest bride" like the other missing woman used by Bigfoot to reproduce. The movie ends with three whooping vocalizations also heard in the distance that are similar to the ones belonging to Bigfoot.
The film was premiered at the 2013 Independent Film Festival of Boston, and subsequently screened within such festivals as Maryland Film Festival. Willow Creek has received generally positive reviews from critics. Review aggregation website Rotten Tomatoes gives the film a score of 86%. The website's consensus states: "Writer-director Bobcat Goldthwait's first foray into horror doesn't break any new ground, but it does wring fresh terror from a well-worn genre formula—and offers a few nasty laughs in the bargain."
