[5][6] It was chosen to compete in the Sitges International Fantastic Film Festival,[7] screening there on 13 October.

[8] Set in 1527 during King Jungjong's reign where plague is spreading in Joseon and rumors are rife that a mysterious vicious creature called "Monstrum" is roaming around the country.

Filming took place in various locations such as Paju, Yangju, Gwangju City and South Gyeongsang Province.

[13] Shim Sun-ah from Yonhap News Agency gave a mixed review and wrote, "Monstrum is the first creature action movie set in the Joseon era and has a suspenseful and entertaining premise, but it is ruined by a predictable plot.

[17] However, the film dropped to second place during the weekend, tailing Searching on the lead by attracted 421,479 moviegoers with US$3.3 million gross.