Sierra Pictures is financing the Patricia Highsmith adaptation and produces alongside Ted Hope and Killer Films’ Christine Vachon [pictured, right]. Goddard directed the two-hour season finale of Downton Abbey. Sierra/Affinity handles international sales.

Susan Boyd adapted the screenplay to The Blunderer from Highsmith’s 1954 novel of the same name about a successful young man whose life unravels when his wife is found dead at the bottom of a cliff.

Boyd optioned the book with her husband William Boyd, the celebrated novelist and screenwriter, who serves as executive producer.

Sierra/Affinity svp of development and production Kelly McCormick will oversee production for the company.

Goddard directed multiple episodes of Downton Abbey as well as Dr. Who, Law And Order: UK, Torchwood and the BAFTA-nominated short Little Sisters.