Complex sentence: Meanwhile, Flint and Holt realise the manager is the money man they lost earlier, and rushing to his shop, they find the manager has already set it alight in an apparent insurance fraud, although in the process locking himself in.
Split into simpler sentences: Meanwhile, Flint and Holt realise the manager is the money man they lost earlier and rush to his shop. They find the manager has already set it alight and in the process accidentally locked himself in.