The Mystery of Solomon's Ring — Thomas Lockhaven

Which would you choose?  Helping an old man that's being kidnapped, or endless plates of delicious pasta?

On this second book of the Ava & Carol Detective Agency series, Ava and Carol were about to take a stroll through Italy, when an old man is chased down and then thrown into the back of a car. At the last second, using sign language he sends a secret message to the girls.
The girls hide in the shadows as the car races away. Fearing for the man's life, the girls begin to track down clues.  Only what they discover this time, is a religious relic that has magical powers. Suddenly evil and powerful villains are chasing them.  The clues lead to France, where Ava and Carol are thrust into a secret battle between the Knights Templar and a group of criminals that will stop at nothing, to get Solomon's Ring.