Greg is in the the biggest shock of his young life. The wall separating his family's apartment from his neighbor's has come crashing down. As Greg gets to know the family on the other side, Lucy introduces him to a hole new world of the neighbors he never knew he had in his apartment complex. Greg and Lucy will have to battle wits against their new archenemy, Mr. Keith, from the lava pit in the basement all the way to the roof of the building. They will have to work together to free the apartment complex from Mr. Keith's diabolical grip.