On June 7, 2018, about 1645 central daylight time, a Beech A23 airplane, N8775M, sustained substantial damage following a runway excursion during landing rollout at the Sedalia Municipal Airport (DMO), Sedalia, Missouri. The private pilot and one passenger were not injured. Visual meteorological conditions prevailed and a flight plan was not filed. The airplane was registered to and operated by a private individual. The personal flight was conducted under the provisions of Title 14 Federal Code of Regulations Part 91. The flight originated about 1600 from the Cape Girardeau Regional Airport (CGI), Cape Girardeau, Missouri. The pilot reported that after 4 normal touch and go landings, he set up for another landing on runway 18. The pilot landed the airplane and the touchdown was soft. Suddenly, the airplane turned about 90-degrees to the left. The pilot applied right rudder and reduced the throttle to idle power. The airplane departed the runway surface, struck a runway light with the right horizontal stabilizer, and came to a stop. The pilot was able to taxi the airplane back onto the runway surface and return to the ramp. A postaccident examination revealed that the right horizontal stabilizer sustained substantial damage. The pilot reported to the responding Federal Aviation Administration (FAA) inspector that the left brake had locked while braking on rollout. A post-accident functional check of the brake system did not reveal any anomalies. Both left and right wheel brake mechanisms functioned properly when visually examined by the FAA inspector. Flight controls were also examined with no anomalies found. The pilot stated that the AWOS had reported wind from 100° at 3 knots about 20 minutes prior to the landing. A post accident weather review revealed that the reported wind conditions at DMO at 1640 were 230 degrees at 7 knots.