The Shadow observed a moving object that could have been an automobile, going into the grounds.
The Shadow had observed the one that opened on the side of the house.
The Shadow let his gaze wander, in order to watch the people about the deck and observe what was going on.
The Shadow, looking toward the outside barrier, observed that it was slightly open.
The wall that The Shadow had observed was to his left.
The Shadow observed that the boutonniere was a fresh one, quite in keeping with the standard.
The Shadow observed these facts in the gloomy light of a single floor lamp.
The Shadow did not observe the professor's order of assurance.
From his unseen vantage point, the Shadow observed them all.
Inside the hall, The Shadow observed the door to the corner room.