Since early childhood, Annie, Jake, and Mason have had a special bond. When Annie's parents die on the same night that she and Mason are married, the three friends decide to raise Annie's newborn sister, Opal, together. Annie struggles to be both a sister and a mother to Opal, a wife to Mason, and a friend to Jake. Not surprisingly, their relationships, already entangled, grow dangerous, too close, on the line. One fateful night the three friends miss the moment when they could still turn back, and they goad each other to step across the line, with shocking, unforeseen consequences.