Grief is easy in the movies. For filmmakers, it’s a shortcut, imbuing characters with emotions that can be grasped quickly. Beyond stating the simplest narrative fact that explains what has brought the character to sorrowful place, there’s not much internal layering that’s required. And any emergence from that aching state can feel so cathartic for an audience that trite turns of character outlook are often accepted gratefully by audiences, even if the progression doesn’t really play plausibly. But Kenneth Lonergan doesn’t do easy. With Manchester by the Sea, the writer-director doesn’t treat grief as a gloss of emotional profundity. Instead, it’s something to burrow into, mercilessly and with fierce attention to the scars that can never truly heal. Without resorting to arch edginess or other artistic self-aggrandizement, Lonergan rejects the most familiar storytelling salves in favor of a depiction of damaged lives that is deeply truthful, where wry comedy can coexist with somber spiritual destitution. And where endings aren’t always neat and clean and satisfying. The aces cast — led by Casey Affleck and Michelle Williams — make those lessons as stark as the lengthening shadows cast by a setting sun.