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New Port Richey, perched on a knuckle of Gulf Coast 35 miles northwest of Tampa, is a typically Floridian enclave of strip malls, subdivisions and brackish waterways. During the 1920s, it enjoyed a brief period of glamour when professional golfers and silent-film actors bought land, built handsome homes and socialized with visiting stars from Broadway and vaudeville at the Hacienda Hotel. But the town owed much of its success to the first of Florida’s many real estate bubbles, and the fantasy ended around 1925, dashing forever New Port Richey boosters’ hopes of its becoming a kind of Hollywood East.

By November 2005, when Alexis and Ronald Dattadeen bought a home there — a cozy ranch house shaded by a generous oak — it was just another Tampa suburb. Alexis and Ronald, who were in their mid-20s, had recently welcomed their first child, A., and within a few years they had another son, D. (The children in this article are identified by their first initial only.) Like his brother, D. had dark hair and big brown eyes. But D. also had a rare genetic disorder that would require many visits over the years to gastroenterologists, neurologists and hospitals.