The One Thousand: Book Three: Black Magic Bus - The One Thousand, #3

To escape pursuit, a fellowship of alien-possessed psychopaths has fled to Europe.  In the mountains of Italy they customize a psychedelically-colored tour bus, intending not only to pick up and murder unwary young travelers, but deliver a cargo of lethal pathogens to a major city in the East.  Only the Team of Seven composed of enhanced humans and benevolent aliens can find and stop them...