Description of Heartland by Davis Bunn
When JayJay Hawkins leaves his ranch and climbs onto a bus, he falls asleep and wakes up on the set of a Hollywood studio. The studio, having just lost the drug-addicted, womanizing actor who has played the lead for 56 episodes, is thrilled he's there--he'll save the show, if only he can get a handle on this startling and bizarre world that, unaccountably, looks much like the world he just left.