Bushels of sargassum had washed up among the rental chairs. They clogged the beach. And so, fittingly, the day began with disappointment. Marjorie hated it, done up in strawberry print and pale as the moon with sunblock on her little face, thick like cream cheese. She scooped and hurled the stuff away from the chairs, scowling, haranguing the clods of seaweed. Gracie, implacable behind her sunglasses, rummaging through something on her phone, wouldn’t look Paul in the face. Paul toed the pile before his chair. “It’s got berries. We’ll make wine out of it.”  Gracie frowned. “I have our tagline:…