The Password to Larkspur Lane delphiniums when a mysterious carrier pigeon lands in her yard. Nancy contacts the registry for the carrier pigeon. Meanwhile, housekeeper Hannah Gruen takes a fall and must be treated at the local orthopedist's office. Her attending physician, Dr. Spires, confides to Carson Drew and Nancy that he was forced to tend an elderly woman for her shoulder under peculiar circumstances: the driver of a car blindfolded him when they drove him there, so he wouldn't be able to guess her location, but the doctor believes their destination might have been someplace called Larkspur Lane. Events led him to believe the
Blue Larkspur he is thought to have been a carrier of the X factor, a genetic trait which causes an extraordinarily large heart, and is only passed on to a stallion's daughters via the x-chromosome, although the basis of this theory has not been scientifically proven and dismissed in scientific circles. Blue Larkspur also produced the Hall of Famer Myrtlewood and Blue Denim, a mare who produced six stakes winners. Blue Denim's most important offspring was her daughter Ampola, who never won a stakes race but became one of the Stud Book's most important foundation mares for Gertrude T. Widener. Blue Larkspur