A 75 year old gentleman with a past medical history of hypertension presented to ED with a several day history confusion associated with auditory and visual hallucinations. He had no past psychiatric history. Delirium was considered as the first differential diagnosis, but no cause could be found on screening blood tests, urinalysis, chest x-ray or CT brain. The episode resolved spontaneously with supportive inpatient care, but a depressive episode ensued. A subsequent cognitive examination revealed impairments of both memory and executive function.