Karel Horák, played by Jan Hartl, and his wife Božena Horáková, portrayed by Veronika Zilková, face the heart-wrenching reality of being childless due to medical issues. While vacationing in a serene countryside house with their neighbors, the Stadlers, Karel takes the initiative to purchase the property after a suggestion from Mr. Stadler. During the renovation, he uncovers a mysterious tree stump that oddly resembles a baby, which he cleans up and presents to Božena as a gift. Captivated by the stump, she names it Otík and begins to nurture it as if it were their own child.
As time goes on, Božena concocts an elaborate scheme to fake her pregnancy, driven by her longing for motherhood. With mounting impatience, she accelerates her plan and pretends to 'give birth' to Otík a month earlier than expected. To everyone's shock, Otík springs to life with an insatiable appetite. Alžbětka, the Stadlers’ daughter, grows increasingly suspicious of the peculiar situation. After reading the fairy tale of Otesánek, the truth about Otík's nature becomes evident. Meanwhile, the creature's voracious hunger leads it to consume odd items, including some of Božena's hair and, eventually, even their pet cat.
Tensions rise between Karel and Božena as Karel advocates for eliminating the creature, while Božena fiercely defends Otík as their beloved child. The situation escalates when Otík devours a postal worker, played by Gustav Vondráček, followed by a social worker, portrayed by Jitka Smutná. With the deaths stacking up, Karel makes the drastic decision to confine Otík in the basement, leaving it to starve. However, Alžbětka takes matters into her own hands, attempting to care for Otík with regular human food. When her attempts are thwarted, she resorts to a haunting method of drawing straws to determine a victim to feed to Otík.
The sinister choice falls on the old man and pedophile, Mr. Žlábek, played by Zdeněk Kozák, who has been harassing her. Alžbětka lures him to the basement, where Otík ensnares him with its vines and devours him. In a tragic twist, Karel himself becomes another victim when he confronts Otík with a chainsaw but falters, calling the creature “son” before relinquishing the weapon. Following this, Božena ventures into the basement only to be heard screaming, implying that she too has succumbed to Otík's hunger. Ultimately, the chaos concludes when Otík disregards Alžbětka's warnings, voraciously devouring all of Mrs. Správcová's cabbage patch, leading the determined old woman to take matters into her own hands against the creature.
