Hints for The Case of the Remaining Border

Hint #1: What Our Heroes Are Up To

The borders and provinces are, of course, those on the standard Diplomacy board. This is The Diplomatic Pouch after all! Switzerland is Moriarty's starting point, and so presumably is passable. The problem is to recreate a route that crosses all inland boundaries once and only once, deducing Moriarty's location. Since no information is given regarding sea travel, sea borders may be crossed without limitation or restriction.

Hint #2: Watson's telegram

Trap failed. Moriarty avoided this province (only) but crossed every other land border but one! Will intercept. Join me.

Watson, as detailed, thereupon rushed off to the remaining border. What was the unwaranted assumption he made in doing so?

Back to the puzzle....