May 3, 2018, about 2241 eastern daylight time, a Cessna 152, N6198Q, was substantially damaged when it was involved in an accident near Tamiami, Florida. The noninstrument-rated private pilot and pilot-rated passenger were seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Neither of the pilots onboard provided statements regarding the accident. The operator reported that the pilots departed Miami Executive Airport (TMB), Miami, Florida, about 1700 for a local flight and were expected to return before dark (about 1900). After flying to Lakeland Linder International Airport (LAL), Lakeland, Florida, they refueled and departed on the return flight in night conditions. During the flight, they encountered instrument meteorological conditions and lost control of the airplane. The airplane entered a spin, from which they recovered, then entered another spin. After recovering from the second spin, the airplane collided with terrain. The operator reported that company policy precluded pilots from flying at night without explicit permission from the chief or assistant chief pilot; the accident pilots did not obtain such approval. The 2153 weather observation at the destination airport located about 11 miles northwest of the accident site, included wind from 130° at 8 knots, 10 miles visibility, few clouds at 1,800 ft above ground level (agl), and scattered clouds at 25,000 ft agl. The next observation at 2253 revealed few clouds at 1,800 and 3,300 ft agl and scattered clouds at 25,000 ft agl. Satellite imagery depicted a cloudy area near and over the accident location. Whether the pilots obtained weather information before departing on the flight could not be determined. Examination of the airframe and engine revealed no anomalies that would have precluded normal operation.