The anthology is framed by a series of eerie stop-motion-animated segments that depict a walking dollhouse featuring a blinking doll face. A living doll hand, which exists separately from the house, scurries around the environment to collect various items for the structure. Within the interior of this surreal dwelling, the viewer sees strange biological functions: a cabinet where bugs and moths enter, serving as a sort of stomach, a room filled with living sewing needles that craft tiny tapestries, and a room containing a morphing apple that functions as the dollhouse's heart. Eventually, the dollhouse discovers a small blackbird, though it remains ambiguous whether the bird is a stuffed toy or an actual deceased animal. The dollhouse places the bird inside a baby doll, but upon the doll's immediate crying, the bird is removed. The dollhouse then enters a room where an unconscious girl lies; upon discovering a small door on the girl's chest, the dollhouse places the bird inside. After some time, the girl awakens, much to the satisfaction of the dollhouse.
In another segment, a young boy named Danny is traveling on a train with his mother, Susan. During the journey, Danny encounters an old man carrying a mysterious red box. The man describes the object simply as "a present" and allows Danny to peer inside. Following this encounter, Danny suddenly refuses to eat any food offered to him. This causes great concern for Susan and her husband, Robert, who take the boy to a doctor only to discover that Danny has lost five pounds since his previous checkup. Danny eventually speaks with his sister, Jenny, and shortly thereafter, she also begins refusing to eat. When Robert attempts to confront Danny about this behavior, Danny whispers something into his father's ear, which inexplicably causes Robert to also stop eating.
Susan is subsequently haunted by a disturbing dream in which her family is happily eating her at the dinner table. However, when she observes Danny, Jenny, and Robert eating happily in reality, she smiles, relieved that her husband and children have returned to their normal habits. As Christmas arrives, Danny, Jenny, and Robert are all severely emaciated, yet they seem completely indifferent to their condition. Danny presents Susan with a gift wrapped in a red box, triggering her memory of the incident on the train. When Susan asks her son what was inside the original box, he simply replies:
> "nothing."
Through a voice-over, Susan reveals the tragic conclusion: all three members of her family eventually died of starvation, with Danny passing first, followed by Jenny and then Robert. Now alone, Susan spends her time searching trains for the man with the red box, driven by a desperate need to know the box's contents, as she feels it is the only remaining way to feel close to her lost family.
In a different story, a woman named Mary is attempting to organize a birthday party for her daughter, Lucy. The celebration takes a dark turn when Mary discovers her husband, David, dead in his home office. Instead of contacting emergency services, Mary decides to hide the body. She spends the rest of the day in a frantic state, trying to keep David's corpse concealed from Lucy, the nanny Carla, and their neighbor Madeleine. In a desperate attempt to mask the body, Mary purchases a panda costume from a man hired to sing a birthday song for Lucy and stuffs the body inside the suit.
During the party, Mary is unable to move the costumed body in time and is forced to seat it at the table. The situation reaches a climax when Carla accidentally bumps the costume, causing it to collapse directly into Lucy's birthday cake. The horror is fully revealed when Carla tries to lift the panda and accidentally removes the head. At this moment, the full title of the film is disclosed as the children scream in terror: The Birthday Party, or, The Memory Lucy Suppressed From Her Seventh Birthday That Wasn't Really Her Mom's Fault (Even Though Her Therapist Says It's Probably Why She Fears Intimacy).
Another segment follows four friends—Paul, Gretchen, Jess, and Jay—on an expedition through the desert. Gretchen struggles with a fear of heights. While exploring, the group discovers an ancient cave painting that depicts an evil spirit. After camping for the night, Gretchen is attacked by a creature resembling the spirit from the painting. The entity takes over her body, effectively wearing her skin as a disguise. The creature subsequently kills Paul and Jay before pursuing Jess. During the chase, Jess falls and breaks her leg, leaving her vulnerable as the Gretchen-creature descends a cliff to finish her off. This particular segment serves as an unofficial sequel to the events of Rosemary's Baby.
The final story involves a doctor who agrees to help a pregnant woman go into hiding, where she adopts the alias "Cora." Years pass, and Cora's son, Andy, is nearing his 18th birthday. Cora is summoned to Andy's school to meet with the principal after Andy violently tore off a classmate's fingernails. The principal apologizes to Cora for having to witness an "outburst" from the victim's mother, but he describes Andy as remarkable. Cora becomes deeply unnerved, realizing that her son seems to have an unnatural ability to entrance those in authority.
Cora's mailman, Chet, suggests that Andy may not be the biological son of her former husband, an actor, and hints that Cora's history is well-known. Andy's transformation becomes physical; his voice changes and his fingernails and toenails evolve into claws. He confirms Cora's worst fears: he is the spawn of Satan, a fate she has dreaded since before his birth. Embracing his dark heritage, Andy forces Cora to bow to him as Satan enters the home to reclaim his son. However, Cora refuses to abandon her child; she embraces Andy and explains the reason they went into hiding, asserting her refusal to give him up. Moved by her love, Andy chooses his mother over his dark destiny. The two hold each other tightly as they suffer a violent assault from Satan, their bones cracking and blood seeping from their noses and mouths until they both perish.
