Pancytopenia is a common hematological abnormality encountered in clinical practice. We here report a 36-year-old male who presented to emergency department with complaints of weakness of bilateral lower limbs, burning sensation in all four limbs with history of loose stools, and vomiting 5 days back. The complete blood count of patient showed pancytopenia with no circulating atypical cells. Bone marrow examination performed showed nonspecific but characteristic findings. After excluding the possibility of infective etiology, a possibility of heavy metal toxicity was suspected in multidisciplinary meeting. The urine and blood levels of arsenic done came out very high, and a diagnosis of arsenic poisoning was made. Patient had multisystemic involvement with features characteristic of arsenic poisoning. The present case was a diagnostic challenge in face of nonforthcoming history. This case beautifully highlighted the importance of multidepartmental approach in such cases to arrive at unerring diagnosis and the unique bone marrow findings, although nonspecific were sufficient enough to indicate the possibility of acute insult to the hematopoiesis.