2030: in a gray and hyper-controlled Milan, Diana and Luca are sent on a mission to Lugano to spy on the exchange of a powerful weapon. Not far away, Edo Zani, Manticore Italy's heir, has to respond to an unexpected proposal from the head of Manticore France, Cecile. In the flashbacks, Diana investigates her parents' suspicious deaths when she meets Gabriele, a mysterious Citadel agent.

Diana and Edo form a secret agreement and make their first move, but they underestimate Cecile's fierce reaction. While Manticore Italy is under attack, Ettore Zani has to step in to stop a war from breaking out. In the flashbacks, Diana completes her training with Gabriele and becomes a Citadel agent.

Ettore sends Edo and Diana to Sicily on a sensitive mission that threatens their alliance. However, under the Mediterranean sun, the two discover they are connected by much more than their objectives. Eight years earlier, Diana infiltrates Manticore and carries out her first mission.