When Ivan visits his grandfather, George, for the summer, George barely notices him. George doesn't like kids. And he doesn't like being called Grandpa, or Gramps, or Granddad. George just wants to be left alone in his laboratory, where he invents amazing things. But within a few days, they become friends. It turns out to be Ivan's best summer ever...until something terrible happens. Can Ivan use his magic vest to travel back in time and stop the disaster?