Riley is having a bad day. All kinds of little things have gone wrong and she's feeling down. Theo and Alex try to cheer her up by getting on with what Megablast does best - write music! But even that hits snags. It all leaves Megablast wondering, are bad days contagious? Meanwhile Kaboom has a new invention that can make anyone spill the beans. His diabolical plan: to use it on Rocket.