Playing in a World Series was more than a dream for the Mets' catcher, it was an ``obsession,'' a goal he had set as a boy and which he pursued for 10 years with the Montreal Expos before he came to New York in 1985. The 1986 season was the climactic one, as the Mets beat the Boston Red Sox in seven games. That Carter is a gentleman and a fine person is evident in every line of this look at the 1986 season, with special emphasis on the playoffs and World Series. His natural enthusiasm and exuberance for playing baseball, his admiration and respect for his teammates, and his devotion to his wife and family are a refreshing change from the usual sports biography. Even controversial topics like the Mike Scott sandpaper episode and the shabby treatment Carter suffered while with the Expos are related with candor and style. Not to be missed. Jo DeLapo, Queens Lib., N.Y.