December 1889: A beautiful client arrives with a tale of ghosts, kidnapping and dynamite on a whisky estate in Scotland, but Mycroft trumps all with an urgent assignment in France. On the fabled Riviera, Holmes and Watson make a terrible discovery that propels the duo northward to the snowy highlands. There, in a 'haunted' castle and among the copper dinosaurs of a great whisky distillery, Holmes realises all three cases have blended into a single, deadly conundrum.