Complex sentence: He meets Cleo, his love interest, who is sought after by Simon, a ruthless cat-box-litter exec. Then Newton, Rover's a guide and friend in Catopolis to help him find his roots.
Split into simpler sentences: He meets Cleo, his love interest, who is sought after by Simon, a ruthless cat-box-litter executive. He then meets Newton, a guide and friend in Catopolis, who helps him find his roots.