Cake WIP

My board is about a boy who has an intense craving for cake while dining at a bakery cafe with his parents. I'm still in the thumbnailing stages, and haven't thought about character designs as of yet. But I pretty much have an idea of how the story is supposed to go: 

Boy sees cake. Boy wants cake. He asks his mom for cake, but is saddened when she says no. Suddenly, two guys dining at the cafe take out guns and attempt to rob the cafe. As one of the thugs is demanding cash from the cashier, his partner happens to see the cake that the boy wants and decides to be a jerk and knock the cake to the floor. The boy is so horrified that his beloved cake has been destroyed that he loses all fear and shoots the thief with a slingshot he has in his pocket. Startled, the thief accidentally shoots his gun at his partner, whose arm gets grazed by the bullet. Two scuffles ensue, one between the boy and the thief who knocked down the cake, the other between the cashier and the thief who was shot. The thieves are eventually overtaken and arrested, and the boy is rewarded with cake for his bravery.