In an unprecedented space mission, a U.S. rocket returns from Venus, bringing with it a surprising passenger: a small and strange alien being, which soon becomes the focus of attention for the scientific community in Rome. As the research team begins to study the peculiar extraterrestrial, they discover that it is not only fascinating but also exhibits accelerated growth and extraordinary strength. Over time, due to its unusual biological characteristics, the creature escapes from the laboratory, unleashing chaos in the city.
The being, known as Ymir, is an impressive blend of reptile and mammal, struggling to adapt to its new environment while wreaking havoc in its wake. The inhabitants of Rome quickly find themselves caught in a mix of fear and fascination. However, true tragedy unfolds when, in its attempt to flee, Ymir tests the limits of science and human nature, facing an inevitable fate as the military tries to contain the threat it poses.
The film fuses elements of science fiction with a strong commentary on the fear of the unknown and the nature of humanity in its relationship with other beings, regardless of their origin. With innovative special effects for its time and a captivating narrative, this story becomes a reflection on the encounter of two very different worlds, revealing both the curiosity and adversity that arise in the face of the unknown.