She has starred in the TV movies The Lost World, Watermelon, Uncle Adolf, A Room With a View, Little White Lie, Just Henry, and The Miraculous Year. In 2005 she starred in the TV mini-series Fingersmith and the TV series The Ghost Squad. In 2009 she starred as Abby Mills in the CBS series Harper’s Island, and from 2012 to 2013 she starred as Katherine in The Paradise. She has appeared on stage with the Royal Shakespeare Company and appeared in the music video “The Scientist” by Coldplay. Cassidy has won Irish Film and Television Awards in 2003 and 2010. In 2007 she married actor Stephen Lord and the pair has a daughter together. Since 2015 she has starred as DC Dinah Kowalska on the TV series No Offence.
