。
She just couldn't get over how strange the story seemed.
Literal
She [topic-は] that story [subject-が] strange seem [can't-help-feeling-てならなかった].
~てならない (here in past as ~てならなかった) is the construction for 'can't help feeling X,' marking an emotion or impression the speaker can't suppress. It pairs naturally with thinking and feeling verbs (思える, 感じる, 気になる) and adjectives like 悲しい. 不思議 ('strange, mysterious, wonderful') covers a broader emotional range than its English glosses — it can mean uncanny, miraculous, or simply puzzling. The phrasing 思えてならない ('seemed irresistibly so') is a slightly literary set pattern that conveys ongoing, unwilled mental preoccupation.