Agent Blake finds the corpse of a child. It is one of a long chain. The murderer is called The Miami Killer by the newspapers. Extralarge assists the police in their investigation. All the murdered children suffered from some kind of ailment and the murderer knew his or her victims very well. The successive victim appears to be Elsie who is asthmatic and Extralarge suspects father Marthy and Elsie's teacher. Then Elsie is kidnapped. Can she be saved?

Jack Costello is a retired cop and now private detective who lives in Miami, who handles a myriad of cases for unusual clients. At his side are old police buddy Sam Bosley and cartoonist-turned-amateur sleuth Jean Philippe Dumas, who is using Costello as an influence and has nicknamed the burly detective "Extralarge." In the second series, Costello faces other dangerous cases, again with Bosley and Archibald, the son of an old friend, who Costello amusingly nicknames "Dumas."

The mafia has decided to expand its gambling business to Florida as well, where however the state laws prohibit such activities.

Dumas is alone in Costello's office when a girl offers him a thousand dollars to take her father, the famous scientist Klaus von Hermann, to his hotel. Dumas accepts the appointment but von Hermann is killed in front of the hotel. The scientist was working in Libya at a gas to use against ozone layers hole and he had instead dicovered a very poisonous gas. Before dieing he puts the secret formula in Costello's jacket. So Extralarge becames a moving target for everyone interested in a mass killing formula.

Joan Bruce, leader of the jazz set at Miami, is courted by two men--Ranson Tate, an unscrupulous villain who deserted his wife on becoming wealthy, and Grant North, a young man who ignores her advances until he saves her from drowning. She is compromised by Tate but ultimately is rescued by North.

Miami is the story of two sisters who have grown up separately. The older sister, Angela, is an exotic dancer with her own touring dance group. The younger, Anna, on the threshold of adulthood, lives in a small town working in sales. When their father dies, Anna looks for and finds Angela. The fascinating, high-strung Angela asks the timid Anna to accompany her on tour and, before long, trouble from Angela’s past catches up to them and the sisters’ love is put to the test.

Miguel and Alicia are a young retired couple. One day, Alicia goes to visit her mother-in-law at the nursing home. Hours go by and she does not return. Concerned, Miguel goes out to look for her, but finds her sitting on the sidewalk. What's wrong with her? What happened during this visit? Alicia does not answer. The following days Miguel tries to find out the reason for his wife's attitude, who remains quiet and still in the same position, while he tries to get everything back to normal.

Jack Costello is a private detective in Miami and he finds out he is being followed by a man. He confronts him and finds out his name is Dumas. Dumas speaks with a French accent and he says he is a cartoonist and he needs Costello's image for his cartoon, but with a different name: Extralarge. Wendy is a black petty thief and when she steals an old pocket watch from Senator Pillinger and two men begin to shoot on her she seeks refuge with Costello.

Alejandro Hernandez returns from Iraq, to learn his father owes a large debt to a group of gangsters who run illegal underground races. Keeping a promise to his best friend who was killed in the war, Alejandro looks up his buddy's wife Luisa. They soon fall in love, without realizing they're both caught up in the same dangerous web. Secretly, Luisa races to make enough money to support her child, Alejandro does so to pay back his father's debt and to keep his family safe from the threats of El Guajo, and his unpredictably violent nephew, El Chulo.

Following the highly dangerous work of one America's most elite police forces and their war on crime.