Alsia was a female humanoid con artist who visited Deep Space 9 in mid-2370. There she met an El-Aurian con artist named Martus Mazur.
Recently widowed, Alsia had managed to put away a bit of latinum every year, just for herself, when she and her husband had run their business together. After he died, she had quite a little sum, but not enough for the future. So to live out her retirement, she decided to invest it all and purchasing the mining concession for the entire Vlugta asteroid belt.
Her "secret plan" was rooted in the fact that her father was a stellar cartographer, and in 2340, he conducted a full spectrum mineralogical analysis of the Vlugta asteroids. He never had the means to follow up on what he found. Alsia's plan was to carry out her father's dream. When his survey results become public, she would get seven times her investment back overnight. Alsia told Mazur this story and won his sympathy towards her investment.
Alsia went ahead with her "plan", eventually reporting back to Mazur that she had gotten word that the Vlugta government accepted her bid. Unfortunately, they wouldn't finalize the transaction unless she commissioned a study on the effects the asteroid mining would have on intersystem navigation. Because all her money was committed to the bid, she couldn't afford the study, which needed to be performed within a week. The cost of the study and the investment was 10,000 isiks, and once she was to begin mining, the payback would be ten times the initial investment. Martus offered Alsia the profits from his own venture, "Club Martus". She took his money and never returned to him to report the results of her bid.
After Martus was arrested, he once again encountered her in DS9's security holding area, upon learning that Alsia was indeed a con artist herself. After taking Martus' money, she attempted to scam Quark with the same asteroid mining story and was later arrested by Odo for her attempt. (DS9: "Rivals")