Book 2 in the Cass and the Bubble Street Gang series! Cass and her best friends, Lex and Nicholas, are the Bubble Street Gang! They investigate crimes, solve mysteries and have brilliant adventures. They've even got their own secret clubhouse.The gang need money and quick, and they have some super-genius ideas on how to make it! Like Operation Start a Company, Make Loads of Money for Nicholas's Project and Probably Also Become Millionaires! But Cass also has a mystery to solve. Who is the invisible boy? And why can't anyone else see him? Join Cass and the Bubble Street Gang as they start Making Millions.