A young man named Atsushi Saito visits his pregnant wife Yuko at a remote mountain hospital known as the pregnant women's paradise. He is looking forward to the birth of their child, but his hopes are shattered when a previously unknown parasitic wasp appears. The wasp targets pregnant women exclusively, injecting its eggs into them so that the larvae feed on the fetus and eventually burst out of the abdomen. Atsushi, who has a deep knowledge of insects, realizes the threat and must fight to protect his wife and the other expectant mothers trapped in the hospital. As panic spreads, a perverted doctor named Onozuka schemes to use the wasp for his own purposes, and some people turn against the pregnant women out of fear. Atsushi races through the chaotic hospital to find Yuko, who begins to show symptoms of infestation, and must decide how far he will go to save her and their unborn child. The story follows the escalating horror as the wasp multiplies, the hospital descends into madness, and Atsushi confronts both the creatures and the dark side of human nature in his desperate struggle to keep his family alive.