"Between the two of us, we've carved up California," says Marcia Muller, shown with husband and fellow novelist Bill Pronzini, about their tendency to set their work in San Francisco and other locations throughout the state.Is Northern California big enough for both Marcia Muller and her husband, Bill Pronzini? For the "Mulzinis," as their friends jokingly call them, there's always a new chapter ahead in a remarkable collaborative life of mystery.