Asthmatic David, summering in Nantucket with the Macy family while his parents are separating, finds an alternative to the ""sissy"" life his mother favors. Salty, the horse a relocated neighbor asked Mr. Macy to sell, becomes the best part of a good life with a loving family. David builds up that drooping ego by riding bareback, learning to skipper, outthinking Bill Macy and rescuing his grandmother on the day of the big storm. He even maneuvers a sale that won't deprive him of his new-found (four-legged) friend--he asks his father to buy Salty and Dad telephones his approval seconds before Mr. Macy takes a check from an interested buyer. The old mane line for another almost-lost soul.