Set during the height of the "blitz" during World War II, Operation Crucible (code-named by the Germans referring to its unique 18th-century steelmaking) is based on the true story of the December 12, 1940 bombing of the Marples Hotel in the industrial city of Sheffield. It took only one German bomb to decimate the seven-story hotel into mere rubble. Four men survived the attack, only to be trapped in one of the hotel’s remaining and intact cellars. Operation Crucible is their story.