It follows a group of university students who, with their professor, visit a remote island in upstate New York to investigate sightings of a Yeti-like creature.

Professor Ernst Prell, an investigator of Yeti sightings, embarks on a field trip into the mountains with four graduate students: Keith Henshaw, Karen Hunter, Tom Nash and Lynn Kelly.

The night before the trip, the professor invites Keith to dinner at a restaurant, where he samples an exotic dish named "gin sung."

After the party, Spencer continues to drink, and upon returning home fights with his wife and cuts her throat with an electric carving knife.

Disgusted that Dr. Prell is going to use their friend's body as bait, Karen reluctantly agrees to help out by taking photos, under the condition that they leave Boot Island whether they succeed or fail.

At the breakfast, Prell and Werner salute the party guests and hosts, toasting the previous schemes which have provided victims.

Prell and Werner explain that the "gin sung" Keith has eaten is actually human flesh, and they invite him to join their cannibalistic society.

They bring in Karen's body, and Laughing Crow, brandishing an electric carving knife, speaks for the first time, saying "Mr. Henshaw — white meat or dark?"

[3] Prior to Shriek of the Mutilated, Roberta had served as cinematographer on the horror film Invasion of the Blood Farmers (1972), directed by Ed Adlum.

[4] Adlum co-wrote the screenplay for Shriek of the Mutilated with Ed Kelleher, and pitched the project to Michael Findlay, whom they hired as director.

[6] She obliged Adlum's request to work on the film as cinematographer because the project had already been written, funded, and its actors cast.

[17] TV Guide called the film "one of the all-time worst, but the unintentional laughs may make it worth a look for those who can stomach inept filmmaking.

"[18] On his website Fantastic Movie Musings and Ramblings, Dave Sindelar wrote, "Though it doesn’t quite reach the insane levels of Invasion of the Blood Farmers, it still earns its place in the annals of bad moviedom, and gets weirder as it goes along.

"[19] James Jay Edwards from FilmFracture gave the film a positive review, writing, "Like most of the quickly produced true-life creature movies of the seventies, Shriek Of The Mutilated is very low-budget and looks every penny of it.

[21] The Terror Trap awarded the film 1.5 out of 4 stars, writing, "While it's true that some low budget drive in horrors are capable of generating some uniquely creepy vibes, unfortunately Shriek is an ineffectual cough that never rises to the occasion".

Their DVD release did not feature the "Popcorn" instrumental song that appears early in the film, due to concerns over likely copyright issues.

[9] Vinegar Syndrome released the film on Blu-ray on August 30, 2022, featuring several crew interviews, as well as an audio commentary with cinematographer Roberta Findlay.