Books in Earthkeepers Series series

It all sort of depends on where it came from. Eleven-year-old Chad and Penny are sorting through discarded "junk," looking for something to recycle. But finding a headless tiger figurine doesn't help clean up anything. In fact, from there on out, things get pretty sticky.Chad and Penny are members of Earthkeepers, a club of concerned kids trying to do their part to clean up the environment. Their tendency to "fall into" mysteries is only slightly less amazing than their ability to unravel mysteries.This time, though, everyone seems involved: the FBI, the local police, a mysterious foreign "business" man, even Chad's mom. The closer they get to the mystery, the greater the danger. Are they up to the challenge?