Writer-director Tamara Jenkins’ darkly funny, bitter and sad portrait of the caretaking of an ailing parent by his adult kids is amusing and moving, sometimes in the same breath. Laura Linney is reliably fabulous as Wendy Savage, a temp from New York City who writes “subversive, semi-autobiographical” plays about her fucked-up childhood at the hands of a neglectful father (the solid Philip Bosco) and an absentee mother. When her father’s elderly girlfriend dies at their home in Arizona, with his own mind being ravaged by dementia, Wendy can no longer avoid taking care of him, and so she and her brother John (an always wonderful Philip Seymour Hoffman), a drama professor from Buffalo working on a book about Brecht, must put aside their deep-seeded resentments and painful pasts, and face up to the need to help their father through his final months with some semblance of dignity. Jenkins’ follow-up to her debut film “Slums of Beverly Hills” (1998) is a good step up. Its mixture of odd moments of human comedy, not-overly-dramatic pathos and thoughtful, heightened realism is endearing (no wonder the likeminded Alexander Payne is an executive producer). Very well-done.