In 1922 Robert Allerton--described by the Chicago Tribune as the "richest bachelor in Chicago"--met a twenty-two-year-old University of Illinois architecture student named John Gregg, who was twenty-six years his junior. Virtually inseparable from then on, they began publicly referring to one another as father and son within a couple years of meeting. In 1960, after nearly four decades together, and with Robert Allerton nearing ninety, they...