 When Nigel is charmed by brilliant student Lorraine to show her their offices (and kiss), a burglar knocks out Sidney, but what was robbed? They find out in Madrid, where Professor Lamenza invited them to follow the trail of the Spanish crown hidden from Napoleons army by Carlos IV, the necessary filters to read lemon ink have been switched, and Lorraine is actually Reena, who has teamed up with her lover Raoul to get the crown which everyone goes in search of in Andalusia, while trying to get rid of the others.