Following on from their previous Misadventure, Holmes and Watson have committed themselves to rescuing Sherlock’s wife Irene, but could she really be working for Moriarty?

Dr Watson unknowingly holds a vital clue to the Professor M’s whereabouts. Meanwhile, Holmes takes them on a hiking expedition in the Scottish Islands, and they end up following a trail of clues which Watson believes are imaginary. And what on earth is Mycroft up to?