Inspector Fabbri and Morini and Rex team up with the secret service to join in the hunt for a terrorist who has threatened to blow up a local conference.

When Countess Clotilde Sanfelice falls to her death from a window of her house in front of two horrified witnesses, a homeless woman who is seen fleeing the house is suspected of having murdered her. Rex and Inspectors Fabbri and Morini investigate the suspicious death.