She holds a secret in her hands as she remembers his dying words, you need to keep this safe! A fire at a disused World War II bunker in Belltrees sets off a train of events that causes disturbance after disturbance in the small community, involving a myriad of characters, from dogs and children to the subjects of secret experiments. The locals in Belltrees feel under threat by the escapees from the bunker, and two of them are murdered in their own homes. Helen, who finds a dying scientist in the park, is entrusted with secret information about the experiments.Two Sydney detectives join a local police taskforce and work diligently to solve the mysteries that surround the events at the Belltrees bunker. A rogue ASIO special agent turns out to be one of the villains. A local radio show host keeps the community informed of developments and eventually becomes involved in the events himself.Susan, initially an innocent victim, ends up being potentially the worst villain.