In Aunt Tilley's house, Kyla and E.B. investigate random objects in the file drawers they inherited from Great Aunt Hermione that show how history connects to who we are and how we live now. E.B. learns about blood-sucking alien sea lamprey that prey on Lake Ontario fish. Zebra mussels from Europe also invaded the Great Lakes when canals and seaways were built. Kyla helps capture a huge escaped python, while a biologist shows E.B. an ash tree infested by emerald ash borers. Many other alien species such as Dutch Elm fungus and Asian carp have found a way to North America and are a causing an imbalance in ecosystems, and they all came here because of human activity