A revolution is under way at a once sleepy New England bank. Forty-five-year-old Frances Fitzgibbons has gone from sweet-tempered loan officer to insatiable force of nature almost overnight. Suddenly she's brazenly seducing the high-school drum major, taking over her boss's office, firing anyone who crosses her, inspiring populist fervor, and publicly announcing plans to crush her local rivals en route to dominating the entire banking industry in...