In a village on Lake Maggiore Andrea’s return from Australia and the wedding of his niece, Paolo, is being celebrated. The enjoyment of the moment is soon to turn into anguish. An unexplainable murder is about to be committed during the wedding reception and it is followed shortly after by another mysterious death. A brilliant marshal of the Carabinieri finds himself involved in a complicated case; the solution of which is kept in the trunk of an old elm tree.