Arachne's Challenge. Book 4 of the Peacetaker Series, #4

A mythological entity thought to be pure myth, forces Stella and Carter to take a deadly challenge. A suicide bomber strikes at an unremarkable department store in upstate California. A week later, two teenage nerds perish in a house explosion that left a crater in the ground but otherwise did little damage beyond its perimeter. A few days later, a dying teenage car thief whispers 'Marseille' to the FBI agents at her bedside. It's sheer coincidence that Carter and Stella plan to start their vacation in Marseille.
Mere hours after their arrival, the relaxing trip turns into a trap. As an ex-soldier, Carter is always ready to deal with danger; this time, however, it's not just terrorists, but car thieves, and artifact smugglers threatening them every step of the way. Perhaps that's why Carter agrees on a small detour. And like many times before, he has no idea he has just traded one danger for another that's deadlier than anything he's faced before.simply because it's something even mythology can't explain.