After finding a nice, secluded spot, they set up their tent, build a fire, and watch the sun set.
After dining, their fire had died down, and they decide to turn in for the night.
They are awoken by the hoot of an owl in the middle of the night.
The sky is beautiful overhead, black as ink, starry and cloudless. Sherlock asks Watson,
“My dear fellow, what do you deduce from the beauty of the sky above us?”
Dr. John Watson replies “Astronomically, I deduce that the universe is vast and has millions of stars and galaxies. Meteorologically, I deduce that we will have good weather tomorrow, as the sky is clear.”
After a short pause, John (now curious) asks Sherlock
“What do you deduce. my friend, from the sky above us?”
“Elementary, my dear Watson. I deduce that someone has stolen our tent.”