Fill in all Safe Squares in the grid. The numbers on the edges show how many filled squares are in each row/column, and in what groups. Cross-reference rows and columns to find them.
A block of 3, then at least one gap, then a block of 1. The gap can be 1, 2, or more squares. Numbers always read left→right and top→bottom.
One row and one column start hidden as a flashing ?. Find 2 correct Safe Squares in that line to decrypt and reveal the real clue.