Complex sentence: Schumacher and Marceau, who have both been expelled from the estate after a fight over Lisette, watch Octave and Christine in the greenhouse; they mistake Christine for Lisette because Christine is wearing Lisette's cape and hood.
Split into simpler sentences: Schumacher and Marceau, who have both been expelled from the estate after a fight over Lisette, watch Octave and Christine in the greenhouse. They mistake Christine for Lisette because Christine is wearing Lisette's cape and hood.