A previously healthy 9-year-old immigrant girl from Mexico was evaluated in the emergency department (ED) with one week of fatigue, fevers, rhinorrhea, and cough. She initially presented to her primary pediatrician, where a complete blood count revealed neutropenia, prompting referral to the ED. In the ED, she was found to be influenza A–positive. Because of dehydration, she received intravenous fluids and was admitted to the pediatric hospital medicine service. After 2 days, influenza symptoms improved, and oral intake increased. However, she was noted to have decreased bilateral lower-extremity strength, absent Achilles reflexes, decreased lower-extremity sensation and proprioception, a positive result on the Romberg sign, and abnormal heel-to-shin testing results. These findings prompted an urgent neurology consultation. After extensive imaging, laboratory evaluation, and further consultations, a diagnosis was established.