Entertaining with slight weaknesses

A thoroughly entertaining episode, exciting plot, where you like to stay tuned. A typical ??? Adventure with mysterious characters, a secret message and a hidden "treasure", all wrapped up in a lonely mountain scenario far from Rocky Beach.
Unfortunately, I liked the resolution then not so good, I found everything a little far-fetched and somewhat unrealistic, for example, the secret tunnel between the two distant houses. Who can and wants something "just so build"? And why, except to three detectives to surprise ??? In the lonely mountains so you could also sneak undetected among the houses back and forth, right?
Likewise, I found it unlikely that the downed pilot (He stribt yes shortly after the crash ...) nor a tour through the mountains makes, devises a mystery and hidden his "treasure" ...
Speaking of "treasure" ... in the emphasis of the hotel owner of this word, I had to immediately think Gollum ... LOL ... good gag!
Due to the above-mentioned logic error I liked the whole story then end up not quite as good, three stars.