In the story of the hyper-flawed Flanagans, whimsy and melodrama come crashing together. What might be frothy in lesser hands becomes, in those of Elizabeth Kelly, remarkably rich. Collie, named for the dog breed, is born into a family as wealthy as it is nuts, in a sprawling house on Martha’s Vineyard. Nine months later, another son arrives, a charming rapscallion beloved by all. Rather than parent, their “professionally Irish” dad elevates drinking into high art, while their mom attempts to illustrate why her own imperious father deserves to be hated, complete with charts. Practical, with a predilection for self-awareness, poor Collie earns his mother’s scorn (she calls him “good little comptroller”) and his grandfather’s admiration. Then an accident recalibrates the dynamics, and suddenly Collie’s no longer just the family’s straight man.