Disgraced ex-Deputy U.S. Marshal Gideon Ryder has been given a second chance to serve his country as an agent of the newly created United States Secret Service. Assigned to investigate a smuggling ring operating out of Galveston Island on the Gulf Coast of Texas, Ryder must navigate his way through the population of immigrants, sailors, former slaves, and ex-Rebels to infiltrate a gang of outlaws more deadly and dangerous than the Secret Service could have imagined.