Ari Aster wrote and directed this glossy horror film, which is so well crafted that for its first three quarters it manages not to insult the viewer’s intelligence. An artist, distraught over her mother’s death, joins a grievers’ self-help group, to which she reveals her mom’s and brother’s histories of mental illness; another mourner invites her to a seance, and soon the heroine’s son and husband are threatened by a malignant, unseen force. Excellent sound design, atmospheric art direction, and crisp editing heighten the tension, and the CGI is mainly reserved for the grand finale. Toni Collette is flawless in the lead role, and there’s fine support from Gabriel Byrne, Alex Wolff, and Ann Dowd. Unfortunately the denouement is a stunning disappointment.