Another flick looking to pack a sequel punch, The Nun II places Taissa Farmiga’s Sister Irene back in the habit and facing off once more with a terrifying spectral counterpart.

Source: https://www.shropshirestar.com/entertainment/2023/09/08/film-talk-latest-movie-releases--celine-song-makes-feature-directorial-debut-with-past-lives/

Father Burke escorted Sister Irene to Romania, where they identified the demon and stopped it with a vial of the Blood of Christ.

Source: https://screenrant.com/nun-2-father-burke-death-what-happened/

In the sequel, Sister Irene is summoned to investigate a string of strange and deadly events and that assignment puts her on a path straight to the place where Maurice is currently working -- a boarding school.

Source: https://collider.com/the-nun-2-what-happened-to-father-burke/

Unfortunately, Sister Irene doesn't know what audiences who saw the previous film already do, which is that Valak has been using Maurice "Frenchie" Theriault's (Jonas Bloquet) body as a vessel, as proven by the inverted cross embedded in his skin.

Source: https://www.slashfilm.com/1383678/how-nun-2-sets-up-conjuring-4-director/