In 1970, right after the triumphant premiere of Stephen Sondheim’s groundbreaking concept musical Company, the renowned composer and lyricist, his director Harold Prince, the show’s stars, and a large pit orchestra all went into a Manhattan recording studio as part of a time-honored Broadway tradition: the making of the original cast album. What ensued was a marathon session in which, with the pressures of posterity and the coolly exacting Sondheim’s perfectionism hanging over them, all involved pushed themselves to the limit.