Complex sentence: A billionaire industrialist whose parents were killed by a mugger when he was eight years old, and traveled the world for several years to seek the means to fight injustice before returning to Gotham, becoming Gotham City's vigilante protector at night.
Split into simpler sentences: A billionaire industrialist whose parents were killed by a mugger when he was eight years old. Traveling the world for several years to seek the means to fight injustice, he returns to Gotham, becoming Gotham City's vigilante protector at night.