Evil Under The Circle (G1: The Guardians)
A chance find of a tunnel under an ancient stone circle leads to a terrible secret, hidden millennia before. As terror strikes, and evil consumes, only one group can help: the Guardians. Their elite team, G1, arrives and must overcome the ancient evil. If they fail, then the very world will be destroyed.
The second novelette in the "G1:The Guardians" series.