The hotel number where the crime takes place is 514. 514 in Chinese slang translates to "I want to die." In South Korea and some Asian countries, the numerical digit 4 is considered an unlucky number and is associated with death (due to the words 4 and death sounding similar in their native languages). The fear of the number 4 is known as tetraphobia and is taken seriously in some Asian countries that sometimes floor levels or rooms with 4 do not exist in hotels and other buildings.
Remake of Spanish The Invisible Guest (2016).