Complex sentence: While in bed with Lucas, Annabel is startled by the appearance of a shadowy, monstrous figure in their doorway; while investigating, Lucas is attacked by the same figure that killed Jeffery and slides into a comatose state.
Split into simpler sentences: While in bed with Lucas, Annabel is startled by the appearance of a shadowy, monstrous figure in their doorway. While investigating, Lucas is attacked by the same figure that killed Jeffery and slides into a comatose state.