This article contains spoilers for the movie "Lamb" Writer/director Valdimar Jóhannsson's nightmare-inducing horror film, "Lamb," arrived in theaters on October 8, promising to disturb audiences with its quiet, unnerving pace and surrealist narrative. Co-written by Sjón and distributed by A24 (of "Midsommar" and "Hereditary" fame), "Lamb" follows Icelandic sheep farmers Maria (Noomi Rapace) and Ingvar (Hilmir Snær Guðnason) as they grieve the loss of their child.