After ignoring Daddy's words of caution, Caillou climbs a tree, breaking a branch and unknowingly hurting Gilbert. Caillou learns to be more considerate of others' needs as he helps nurse Gilbert back to full health.
The tree in the garden falls down during a storm and the family reminisces about all their memories with the tree. In the flashbacks with Gilbert, Rosie and Mommy who planted the tree, gave Caillou an idea to plant a brand new tree.