Complex sentence: The recording is shown to the Papal conclave, and when it dawns on McKenna that he has been exposed he flees to a remote recess in the building where he is able to commit suicide by setting himself on fire.
Split into simpler sentences: The recording is shown to the Papal conclave, and when it dawns on McKenna he has been exposed. He flees to a remote recess in the building where he is able to commit suicide by setting himself on fire.