。
She went inside to fetch it.
Literal
She [topic-は] that [object-を] [to-fetch-取りに] inside [into-へ] [went-入っていった].
Two purpose constructions and a directional auxiliary stack into one motion. 取りに ('to fetch, to get') uses the masu-stem 取り plus に for purpose of motion — 'in order to get.' 入っていく ('go in, head inside') chains the motion verb 入る with the directional auxiliary いく ('go away from speaker'), so the going is away from the watcher's vantage point. Compare with 入ってくる, which would be 'come in toward the speaker.' This kind of layered directional grammar is what gives Japanese sentences their precision about whose perspective is centered.