Complex sentence: Knowing that entering into a relationship with Nobu will destroy any chance of her being with the Chairman, Sayuri is distraught and devises a plan, enlisting Pumpkin's help to have Nobu catch her seemingly being intimate with the Colonel.
Split into simpler sentences: Knowing that entering into a relationship with Nobu will destroy any chance of her being with the Chairman, Sayuri is distraught and devises a plan. She refuses and enlists Pumpkin's help to have Nobu catch her seemingly being intimate with the Colonel.