Casts may be associated with, and mask, serious life-threatening complications, including infection, compartment syndrome, and deep vein thrombosis with or without pulmonary embolism. A 43-year-old woman had necrotizing fasciitis associated with a closed-reduction casting of a tibial fracture. Her treatment highlights the importance of removing a cast and assessing the skin and tissue underneath for signs of infection in patients with suspected infection. Thorough assessment, early diagnosis, and early intervention in necrotizing fasciitis and sepsis are important to improve patients' outcomes.