This film is about a 17-year-old Cassandra Mortmain (Romola Garai), and the fortunes of her eccentric family, struggling to survive in a decaying English castle. Her father (Bill Nighy) is desperate to repeat the spectacular success of his first novel, but hasn't written a word for 12 years; her exquisite sister Rose (Rose Byrne) can only rail against their fate, and their Bohemian step-mother Topaz (Tara FitzGerald) is no help at all. Salvation comes in the form of their American landlord ...