This is another in the series of "wanted" posters that be found within a campaign setting.
-Where has he gone? How did he go missing? Was this a result of an enemy (or a disgruntled wife/lover)? Is he not really missing but rather hiding (in which case the author of this poster may be seeking to do him harm)? The High Merchant title implies he is a man of great wealth and importance.
-It being a tower implies a mage type. Is the person who put up the poster concerned for this person's welfare (since it is implied he may still be alive) or is the person hoping the characters will kill this Milland individual?
-Milland may have put this poster up himself and he has layered this tower with various tests and traps. This was all done to see who could reach the end. It is such a group that he wishes to hire for a dangerous mission.