Massachusetts State Police Agent Lili D'Amico and retired engineer Gil Novak were enjoying the last couple of weeks of their first winter together in Florida. With a little mahjong and a little fishing, they were having fun, making new friends, and getting used to living with each other. Responding to a commotion, Lili finds her neighbor Martha being strangled and near death. Lili confronts the attacker and ends up having to dispatch him. Lili accompanies frail Martha to her home in New Hampshire, where another assassination attempt occurs.

While Lili continues her involvement in Martha's case, Gil is asked to consult on a separate case about recently dug tunnels that have mysteriously appeared in his hometown of Greenfield, Massachusetts. A retired robotics engineer, Gil is recruited to build and operate a robot to inspect the tunnels for clues to their origin.

In this thriller, Gil and Lili end up working together on both cases, as more people are pursued by unknown pursuers with obscure motives. There is a lot going on in this book, with aspects tying to infamous events in Native American and global history. This is Hy Shaw's second book in the Gil Novak and Lili D'Amico series.