Forbidden - Richard Hammond - Bog

When Gilly McMahon watches her older brother, Cracker,
and his friends, Trann and Bone, disappear over the cliff in
front of their family's holiday shack on a secret expedition
she is determined that she will not be left behind.
Accompanied by her cousin Bobby she follows the boys
around the rocks to Pretty Point where she discovers dozens
of black onion-like bags filled with stinking black shells in
Cracker's secret cave.
Cracker is annoyed that Gilly has made such an exciting
discovery - it is his expedition after all.