When Kate's brother Liam is having a science-themed birthday party the very same day that the science club in Kate's school is planning a special rocket launch experiment, Kate isn't sure how she'll manage to do it all: be a great big sister AND a great science club member. But with a little help from chemistry--and her friends--Kate figures out a way to be in two places at once. That is, until she is late to pick up the ice cream cake, which means Liam won't have a birthday cake for his party! Will science be able to save the day?