Complex sentence: Two thieves rob a large fancy house when the owner is away, but when a visitor mistakes them for the owner, and they find out about a casting party misscheduled for that day, they decide to stick around for fun.
Split into simpler sentences: Two thieves rob a large fancy house when the owner is away. But when a visitor mistakes them for the owner, and they find out about a casting party mis-scheduled for that day, they decide to stick around for fun.