It's the classic horror formula: young men and women spend a night of terror in a remote Western-style mansion.
Literal
Young men-and-women [subject-が] remote Western-mansion [at-で] terror [possessive-の] one-night [object-を] spend [quotative-という], horror [possessive-の] standard-style is.
Describes a horror movie cliché. 人里離れた (remote from human habitation) is a set phrase. 洋館 (Western-style mansion) evokes a specific Japanese horror setting. ~という at the end quotes the entire scenario as the content of the 定番スタイル (classic formula). 定番 (classic/standard) is common in entertainment criticism.