The "One Man" in the title refers to George Mortimer "Mort" Cecil, who married Sarah Jane Roelke in 1867, and lived between Hyattstown and Comus in upper Montgomery County, Maryland, where the couple had thirteen children. This book contains genealogical records of related Cecil family lines of Montgomery County, and allied families, with individual chapters devoted to the descendants of each family: Cecil, Roelke, Wolfe, Linthicum, McElfresh, Hyatt, Davis, Henckel, Mattingly, Beall, Mahone, Hebbard, Blood and Bradford. The genealogical records for members of the Cecil and allied families can be traced within the author's family lines. Each family line opens with its earliest immigrant ancestor. Interesting biographical tidbits augment many records, and these family genealogies are enhanced by numerous delightful illustrations and vintage photographs. A bibliography and a full-name index add to the value of this work.