World War I. A tent hospital has been established on the grounds of a crumbling French mansion, somewhere behind the front lines where the shelling over no man's land is closer than anyone would like. Nurse Mary Wellsley wakes in a stinking morgue with damaged vision and a fractured memory — mustard gas, she is told, and a woman in gray moving through the dying. She is able-bodied enough to work and has medical training that the wounded soldier beside her needs. But somewhere outside, her fellow nurse Nancy is alone, possibly in the trenches, and Mary needs to find her. Something darker has been building in the mansion for weeks: figures at the windows, a piano heard at night, creatures in the woods, and a ghostly child dragging something through the rubble. Obscurium is a quiet horror game about what waits in the spaces between survival and understanding.