Playwright Katori Hall’s residency at Signature Theatre resumes with this theatrically engrossing play based on actual events in Rwanda in the early 1980’s when three young women at a Catholic school claimed to have visions of Mary. As the play opens, Father Tuyishime (Owiso Odera),a young handsome priest and Sister Evangelique (Starla Benford), an older martinet nun in charge of the students — two stock characters who could be right out of John Patrick Shanley’s Doubt — are arguing about what to do with 17-year-old Alphonsine (Nneka Okafor), the first to claim to see the Virgin. The priest secretly hopes the apparitions are real while the nun wants to stamp out attention-seeking nonsense. When another student, Anathalie (Mandi Masden), begins to see the visions, Sister Evangelique enlists Marie-Claire (Joaquina Kalukango), the eldest student and a bit of a bully, to interfere should there be other apparitions. Marie-Claire too sees the Virgin in the gripping scene with gasp-inducing special effects that concludes the first act. When word gets out about the visions, the long absent Bishop Gahamanyi (Brent Jennings) shows up and threatens to close the school if the rumors are not contained. Eventually the Vatican sends Father Flavia (T. Ryder Smith) to investigate. The manner in which he tests the girls is barbaric. As the visions come to be accepted, there is much shifting of positions among those who at first belittled the visions and those who supported them. Some are motivated by crass economic considerations, others by faith. But few are able to accept the warning of a coming bloodbath the apparitions portend. In restricting herself to the immediate period of the visions, Hall does not supply much context for what happens. The audience is expected to know in advance about the tribal rivalries between Hutu and Tutsi and the massacres that took place in Rwanda a decade later. That narrowing of focus may rob the play of a bit of its import but not of its theatricality. Rachel Hauck’s modular set is attractive and efficient. Peter Nigrini’s evocative projections add much to the atmosphere. Greg Meeh and Paul Rubin create some marvelous effects. Emily Rebholz’s costumes are very good. Director Michael Greif keeps things moving. One word of caution: a walkway that bisects the theater between rows F and G is used for part of the action, particularly in the second act. If your seat is in Rows A-F, you either will miss some of the action or twist your neck trying not to. Running time: 2 hours 35 minutes including intermission.