The Looming Lamplight

The second in the series featuring the guinea pig detective and his sleuthing cousin
 
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 on and off. 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.