"A stunning addition to the Scientists in the Field series that explores mercury pollution found in the rivers and streams of Western Montana that might cause harm to humans--and the extinction of the entire osprey species."--

Callum becomes friends with Iona, a practically feral classmate who has discovered an osprey, thought to be gone from Scotland, on Callum's family farm, and they eventually share the secret with others, including Jeneba who encounters the same bird at her home in Gambia.