Chicago Nordejoong is a diver.
She lives and works out of Miami specializing in capturing exotic fish on contract. She is not an agent, would not want to be an agent, and is annoyed at being put into company with an agent. She likes what she does and the solitude that it brings, with the exception being the young assistant she is training and helping get a better life.
Into her life without bidding or desire comes Alex Sanders, an agent with a federal task force connected to the DEA, working drug smuggling cases in the Caribbean. He is not looking for a partner or a relationship; he is hunted bad guys who kill without hesitation just to have a boat to run their drugs in with.
Neither Chicago nor Sanders is interested in international intrigue or dealing with enemies of the state but both get involved nevertheless.
As the series begins, Chicago, the beautiful product of a Norwegian sailor and a Tobago woman, has a small boat which she uses to travel the regions off Florida and the Bahamas. She earns most of her living capturing fish of all sorts for large aquariums around the country. She augments this with diving instructions and tours. She is in her early thirties.
Alex Sanders is a drug enforcement agent trained to fly airplanes to search for and apprehend smugglers. He has been doing for quite a number of years, making his age somewhere close to mid-to-late thirties.
They do not know each other when the series begins but meet very quickly into it and begin an interesting love-hate relationship. Both are independent and not given to giving in (i.e., stubborn). As the series progresses, they grow close, drift apart, and come together again, all in the backdrop of activities they would rather avoid but cannot.