After filling out answers for the crossword clues and searching for those answers in the grid, solvers may see that
most of a word is present, but some letters seem to be missing. A potential break-in is solving the clue
Bridge in San Francisco (6 4) to
GOLDEN GATE, and seeing the letters
GOLD*TE in the grid, where
* is a blank square.
As it turns out, every pair of clues cross the same blank square. In the example above, GOLD*TE goes diagonally up left through a blank square, and the paired clue, Souvenirs (9) clues the word MEMENTOES, which goes horizontally right through the same blank square as M*OES, missing the letters EMENT.
Concatenating the missing letters from the clues, in order of clue phrase, comes close to spelling a word.
Specifically, a ceremonial word. The previous example omits the letters ENGA and EMENT, which is one letter off the word ENGAGEMENT.
The additional letter is the needed piece of information from each clue pair. Filling in each missing letter into the blank squares in the puzzle, and reading top-to-bottom, left-to-right, spells the final answer.