Holly must solve the puzzle of an old legend if she and the other mermaids are to stop the toxic waste leaking from a wrecked ship, threatening a family of turtles living nearby, and get back to their vital mission for Queen Neptuna.

After discovering tainted water in the creek near his grandmother's cabin in the Kentucky hills, senior Roy Linden slowly uncovers a connection between his high school team's new star quarterback, his own football future, and the source of the pollution.

A search to find the magical conch shell and restore it to its proper home deep in the Himalayas sends Anand and Nisha to the bleak futuristic city of Coal, where the air and water are polluted and the upper classes live in luxury under hermetically sealed domes.

Seaside Sanctuary Marine Wildlife Refuge in South Carolina has a wild pen which is supposed to be healthier for the marine animals brought there, but the three new dolphins are getting sick and no one can explain why; Elsa Roth, whose parents work at the sanctuary, is convinced that a local chemical plant is to blame, but since the water tests do not show contamination she is having trouble getting the adults to believe her--and if she is going to...