When Douglas Davenport was evil in the past, he accidentally spilled an evil virus onto a black metal skull. When Douglas found an uninhabited island at the ocean, he buried the skull there.
Years later, when Perry went to that island, Chase, Bree and Leo went to find her. After Perry found a buried skull on the island, she brought it back to the Davenport Bionic Academy, where the virus infects Bree and Chase. However, Leo, Douglas, Adam and the others manage to cure Bree and Chase by injecting them with nanobots.