The leading word of attributive clause is that, the antecedent is plural, and the verb after the leading word is singular or plural? He likes movies that____ (be) about scary monster.

The leading word of attributive clause is that, the antecedent is plural, and the verb after the leading word is singular or plural? He likes movies that____ (be) about scary monster.

Plural, follow the antecedent
The premise is that the antecedent is a noun before the predicate