Valerie and Samantha are looking forward to a day of fun at the Science Museum in St. Paul, playing with gadgets and doing science projects in the lab. What they don't expect are the gnomes, Marcus and Michael, showing up again and sending them on a wild scavenger hunt through time. Meeting interesting people from history, discovering new musical instruments, ancient healing devices, and even a torture chamber are a part of their oddest adventure yet. So is Val's big brother, Darrell, who shows up to help just when he's needed most. Collecting a series of items-all with intriguing symbols-during this adventure is one thing; what their choice will be to do with them at the end of the hunt is another altogether.