Start of a brainteaser whose answer appears in order, from top to bottom, in this puzzle's circled squares

Question:

Length:

Similar Crossword Questions:

Mark that appears four times in this puzzle (hint: the baseball player who's the answer to this puzzle uses one, too)
Question asked by a customs officer or a kid on Christmas ... with a hint to this puzzle's circled squares
Company whose movies, not counting sequels, are all included in this puzzle [Circled Squares: 2009]
Movie good guys responsible for the circled squares in eight long puzzle answers
What the three sets of circled squares in this puzzle represent
Gather wealth by exploitation ... as hinted at by this puzzle's circled squares?
What's revealed by connecting the special squares in this puzzle in order
Drink cooler ... or a hint to six squares in this puzzle's answer
Letter that appears at least once in every single answer in this puzzle
Secret get-together, or what occurs literally in each of this puzzle's circled squares
Work by Sir Edward Elgar hinted at by this puzzle's circled squares
Geographical features ... or what the circled squares in this puzzle represent
Welcome mat spot (our puzzle title hints at the theme revealed by the pattern of circled squares)
Company "sorted" in this puzzle's circled squares
Very distant or different (and a hint to what's hidden among the Across answers, in their logical order, from top to bottom)
Street weapon ... or a hint to the circled letters in this puzzle
Start of an order to an attack dog
Possible puzzle start
Triatomic gas in a thinning layer ... and, symbolically, what appears in this puzzle's four longest answers
Landmark inaugurated 3/31/1889 whose shape is suggested by nine squares in this puzzle's completed grid
Vicissitudes of life, as for the inventor named in the circled squares?
Puzzle based on Latin Squares
Weather comment represented visually by this puzzle's circled letters
Artwork using both paint and collage, e.g. ... and a hint to this puzzle's circled letters
Secret military mission ... or a hint to the circled letters in this puzzle?