Clive Bellamy is a Yeoman Warder (also called Beefeaters), one of the dedicated Tower guards and twenty-five year military veterans who live on the premises of the Tower of London and manage its day to day operations as a world heritage site, living museum and Crown Jewel vault. Clive’s military career took a toll on his family. After an acrimonious split, his ex-wife moved to America with their daughter Ashley.
Ashley comes to visit Clive and stay in his quarters within the castle but their reunion is overshadowed by a bomb scare which requires the Tower’s evacuation. She disobeys orders and stays within the Tower to be close to her dad. The police cordon off the entire fortress and Ashley and Clive are trapped inside the compound. Clive realizes the bomb scare is a cover for a Crown Jewel heist and he trains Ashley to use the Tower’s medieval defenses. They must fend off the brutal thieves using castle warfare tactics. Will father and daughter survive and navigate their own past in the process?