Sienna had designs on Darren so hatched a plan to split Darren and Nancy up. Nancy had become addicted to codeine but managed to wean herself off. Sienna started spiking her tea with codeine to make it look like she was on it again, acting all wild and the sleeping the next, which started the fights. They separated and sienna moved in to help with the baby etc. sienna and Darren sleep together, she "claimed" that she's pregnant, convinces D to be a family, sets nancy up by telling her D wants N out of his life and convinces her to run away with Oscar (her baby) and Charlie (her nephew) and hands N her car keys.
Meanwhile Sienna then cuts her head, turns the gas on, turns on the ovens and ties herself to the table leg making it look like N attacked her.
Car chase ensues, almost killing herself and the kids, she's arrested.
