Everyone's lending a helping hand today. Caillou plans a surprise birthday party for Grandpa with Grandma's help. He and Grandma get everything ready, and Grandpa is very surprised and very happy. Caillou really likes to play with Leo's pet hamster and would love to have one of his own. He doesn't realize how much hard work having a hamster can be until he offers to look after Leo's pet while Leo and his parents are out of town. He soon realizes it's not all fun and games - especially with Gilbert around! Mom is upset when the mailman only brings bills, bills and more bills. Caillou and Dad decide to make a nice letter for her and they give it to the mailman to deliver. Mom is thrilled to get such a nice letter from Caillou. On another day, Caillou is really looking forward to a special day with Dad, but Dad gets a bad cold and has to stay home. Caillou is pretty disappointed at first, but then with some help from Mom, Dr. Caillou looks after patient Dad.