Pretty Coco LaSalle, a female pirate, attacks and robs Yancy's riverboat. The most important object stolen was a diamond necklace belonging to the government of Mexico. Yancy agrees to help John Colton recover the jewelry and learns that Coco's price is very reasonable - that Derringer escort her to the masked ball for Mardi Gras. Unfortunately, one of LaSalle's men is unhappy with the bargain and is determined to steal the necklace from the pirate queen before the jewelry can be returned to its rightful owner.
—David Bassler