Complex sentence: Mitchell and Petrillo returned to nightclub work but, according to Petrillo, Lewis threatened to boycott anyone who booked them and club owners caved in, not wishing to spoil their chances of someday hiring Martin and Lewis.
Split into simpler sentences: Mitchell and Petrillo returned to nightclub work, but Lewis threatened to boycott anyone who booked them. Club owners caved in, not wishing to spoil their chances of someday hiring Martin and Lewis.