Complex sentence: Reduced to two, Liz suggested a suicide pact, whereupon Mike professed his love for Liz, prompting Liz to climb the ladder towards the shelter's entrance and unlock the door.
Split into simpler sentences: Reduced to two, Liz suggested a suicide pact, whereupon Mike professed his love for Liz. This prompted Liz to climb the ladder towards the shelter's entrance and unlock the door.