The looming lamplight

Coco Carlomagno, the well-respected (if somewhat easily startled) Chief of Police, has run into an unusually difficult problem.

From his office high in the Obelisco, Buenos Aires' tallest building, he can see a light turn off and on.

Could it be a message? How can he possibly decode it? In desperation he once again calls on his clever cousin Alberta to help him solve the puzzle of the looming lamplight.