Haemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal disorder. It is challenging to diagnose due to its rarity and variation in clinical presentation, laboratory abnormalities and underlying aetiologies. A reproductive-aged woman, gravida 2 para 1001 at 27 weeks gestation presented with fever, hypotension and subacute upper respiratory infection. She delivered a male infant by caesarean section secondary to fetal distress. Subsequently, she was diagnosed with T-cell lymphoma and secondary HLH. Despite management with supportive care and multiple chemotherapeutic agents, she ultimately died of multiorgan failure. Patients with HLH secondary to malignancy have a particularly poor prognosis. This case highlights the importance of considering secondary HLH in the differential diagnosis of a patient with fever, pancytopenia and systemic symptoms of unclear aetiology in pregnancy.