The studio discovered a trained German Shepherd named Rin Tin Tin in 1923. The canine made his debut in "Where the North Begins", a film about an abandoned pup who is raised by wolves and befriends a fur trapper. According to one biographer, Jack Warner's initial doubts about the project were quelled when he met Rin Tin Tin, "who seemed to display more intelligence than some of the Warner comics." Rin Tin Tin proved to be the studio's most important commercial asset until the introduction of sound. Screenwriter Darryl F. Zanuck produced several scripts for Rin Tin Tin vehicles and, during one year, wrote more than half of the studio's features. Between 1928 and 1933, Zanuck served as Jack Warner's right-hand man and executive producer, a position whose responsibilities included the day-to-day production of films. Despite the success of Rin Tin Tin and other projects, Warner Bros. was unable to compete with Hollywood's "Big Three" – Paramount, Universal, and First National studios.