DIGOS is the Italian police agency responsible for investigating anti-terrorism threats.
Milan's DIGOS, which operates out of the Questura (police headquarters), is one of the most elite branches in Italy.
Thirteen Days in Milan is the first book in the series about an American single mother, Sylvia de Matteo, who is taken hostage at Milan’s Stazione Centrale by terrorists who assassinate a Berlusconi finance official.
The second book, No One Sleeps, features DIGOS agents searching for a clandestine cell of Muslim terrorists in Milan who have received chemicals from Pakistan to make toxic sarin gas. No One Sleeps was published in December 2017.
The third book in the series, Vesuvius Nights, will be published in March 2019.