Caillou: Mystery ValentinePaperback, 4 January 2016

It's Valentine's Day and Caillou is invited to a party at his best friend Leo's house. Caillou prepares special Valentine cards for all his friends. When he gets to the party and hands out his cards, he finds a mysterious Valentine addressed to him! It's not from anyone at the party. A little investigation back home leads him to his secret admirer.