Complex sentence: Bullitt picks up his 1968 Ford Mustang GT and sees he is being tailed by the two hitmen; he turns the tables and follows them, resulting in a car chase at the end of which the hitmen are killed.
Split into simpler sentences: Bullitt picks up his 1968 Ford Mustang GT and soon discovers he is being tailed by the two hitmen. Later the hitmen realize Bullitt has turned the tables and is now following them, resulting in a car chase at the end of which the hitmen are killed.