In 1996, when Maya Forbes was twenty-eight, an alumna of “The Larry Sanders Show” with a studio development deal, she introduced her future husband, Wally Wolodarsky, to her father, a descendant of two of the older and more prominent families in Boston. They were with Forbes’s sister, China—the singer of a band called Pink Martini—and China’s boyfriend at the time, the director Wes Anderson, who was working on “Rushmore.” The group picked up Maya and China’s dad, Cameron, at McLean, the psychiatric hospital outside Boston where he stayed during bipolar episodes, and took him to lunch. Cam ordered a mushroom omelette, mushroom toast, mixed mushrooms, and a giant mushroom that took up an entire plate. He was a heavy smoker. After lunch, they dropped him back off at McLean. He…