A chronicle of the original Mercury astronauts in the formation of America's space program: Alan Shepherd, the first American in space; Gus Grissom, the benighted astronaut for whom nothing works out as planned; John Glenn, the straight-arrow 'boy scout' of the bunch who was the first American to orbit the earth; and the remaining pilots: Deke Slayton, Scott Carpenter and Wally Schirra.