Complex sentence: When Betty calls to leave a message about borrowing a Buick LeSabre for her birthday, her husband tells her to take a different car, as the LeSabre (unknown to Betty) has stolen drugs hidden in the trunk.
Split into simpler sentences: When Betty calls to ask about borrowing a Buick LeSabre for her birthday, her husband tells her to take a different car. The LeSabre (unknown to Betty) has drugs hidden in the trunk.