March 1922, Bavaria. Hindkafik Farm is hidden deep in the jungle, with its nearest neighbor a twenty-minute walk away.
The Franz family of six lives here - the stubborn father Franz Gruber, the semi-demented old mother Old Liz, the widow Margaret who keeps a secret, the seven-year-old granddaughter Little Liz, the two-year-old Thomas, and the new maid Erna Baumgartner who just arrived that afternoon.
The footprints can only go in but not out. There were footsteps in the attic. The key is missing. The former maid Petra resigned in a hurry, saying that "there was someone above". Franz placed an ax in each room, but never opened the trap door.
Late at night on March 31, someone came down from the attic.
Six people were killed. The murder weapon was a pickaxe.
But the murderer didn't leave. He stayed for several days in the house where he had killed six people - cooking, eating, feeding the animals, and sleeping in the dead man's bed. He washed the dishes, stacked them and put them back in their place.
Who is it? Was it her husband Rudolf Gabriel, who was "killed" in the Somme but had no body? Is it Hermann Schlittenbauer, the neighbor whose marriage proposal was rejected and who has held a grudge for many years? A stranger whose name you will never know?
Munich detective Ruprecht only believes in evidence. He walked into the loft, squatted beside the hay bed, and shone his flashlight around the cans, the pickle jar, a section of beeswax, and a razor that belonged to no one in the family.
One hundred years have passed. The footprints on the snow still only pointed in the forward direction.
