“Warning: If you receive a box from a Dr. A. Summers who lives in Florida, DO NOT OPEN under any circumstances, unless you’re up for a crazy whirlwind of an adventure.”
This is how Chloe Nickelson begins her encounter with Time Travel. So what was in this mysterious box from a complete stranger? Why would she warn against something as innocent as opening a package?
The answers are in Time Brigade; Ancient Beginnings.