Complex sentence: During breakfast loud voices are heard in the garderobe and not the main door; the Marschallin believes that it is her husband who has returned unexpectedly from a hunting trip and has Octavian hide behind the bed.
Split into simpler sentences: During breakfast loud voices are heard in the garderobe and not the main door. The Marschallin believes that it is her husband who has returned unexpectedly from a hunting trip and has Octavian hide behind the bed.