A devoted and mild-mannered couple decides to kill spouse's parents...Patricia and William Wycherley were shot dead at their home in Mansfield, Nottinghamshire, on the May Day bank holiday weekend in 1998. The next working day, their daughter, Susan (Olivia Colman), cleared £40,000 from their account. And she and her husband, Christopher (David Thewlis), continued to withdraw large sums of money from their account for the next 15 years, spending thousands on Hollywood souvenirs, particularly autographs of movie star Gary Cooper...