A Chinese scientist comes to the US but is kidnapped straight away from the airport and switched for his look-alike, which soon suffers death in mysterious car accident. Young girl who says she's scientists niece comes to Jack 'Extralarge' Costello and asks him to find her uncle. Extralarge starts investigation, but someone doesn't want him to learn the truth and whole case is complicated even more when he finds out that the girl is not the person who she claims she is.

Costello's former opponent, Gonzales escapes from prison and seeks revenge against Costello. He implicates Costello in a criminal case, who even goes to prison, but it soon becomes clear that Gonzales' plan is worthless.

Extralarge and Dumas by chance foil the kidnapping of a small girl. What apparently seems to be a normal kidnapping for the purpose of extortion hides a vendetta between drug traffickers. In fact, the girl’s father, Eduardo, is the right-hand man of the Medellin cartel. Eduardo has decided to change his ways, but the other men in the cartel will not permit him to. So Eduardo, in order to blackmail his bosses and as insurance for his life and that of his daughter, hides an enormous consignment of diamonds at a bank which he will return to the traffickers once he is safe. But luck is not with the him. A band of robbers break into the bank where the diamonds are being kept and Eduardo’s guarantee of survival disappears. Terrorized, he goes to Extralarge asking him for protection without however informing him of the real situation, while his daughter is kidnapped by the cartel’s men.....

A series of mysterious murders throw the south of Florida into confusion: an individual dressed as a Ninja warrior runs through his victims with a long sword, launching incomprehensible messages. Extralarge and Dumas are appointed by the police to investigate despite the fact they have another case to solve: the protection of an important politician who has received death threats. Extralarge discovers that all the Ninja's victims were part of a team of sappers in Vietnam responsible for the destruction of a small village, Nang Ky. The death squad was headed up in fact by the politician who the detective is protecting. Extralarge also finds out that Nang Ky was the most isolated outpost in Vietnam and had become a paradise for perdition and vice run by a number of American officers who, towards the end of the war, arranged for it to be destroyed by napalm so as to cancel any trace of their abuse.

The mafia has decided to expand its gambling business to Florida as well, where however the state laws prohibit such activities. The lawyer Clemente is appointed to find ways of evading the legal loopholes and make the plan possible. Clemente discovers that the Indian reserves of America are exempt from the normal regulations of the States and prepares an action plan: he presents a project for the construction of an enormous shopping centre which, once approved, will instead become the biggest casino in America. An Indian chief, Thomas, opposes the project and is thus killed.