On June 16, 2013, about 0130 central daylight time, a Beech model 58P airplane, N5958P, was substantially damaged when it impacted an airport sign during a rejected landing on runway 14 (6,491 feet by 150 feet, asphalt) at the St. Paul Downtown Airport (STP), St. Paul, Minnesota. The pilot and one passenger were not injured. The second passenger sustained minor injuries. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Instrument meteorological conditions prevailed for the flight, which was operated on an instrument flight rules flight plan. The flight originated from the Duluth International Airport (DLH), Duluth, Minnesota, about 0015.The pilot stated that after touching down he realized that he had landed long and elected to reject the landing. He reported hearing a "thump" during the initial climb. He returned for a landing and, during the rollout, realized that the right brake was not functional. He used differential thrust to taxi to the ramp. During a postflight inspection, the pilot observed damage to the lower fuselage. A postaccident examination revealed that the right side of the lower fuselage and cockpit floor had been damaged beneath the co-pilot/right front passenger seat. Damage was also observed to an airport sign off the right side of runway 14, in the vicinity of taxiway A1. The pilot stated that there were no failures or malfunctions with the airplane before the accident. He added that there were no flight control issues during the go-around after the impact with the airport sign.