«The Cask» by Freeman Wills Crofts

A suspicious cask arrives in London dock which when unloading slips and cracks open to reveal gold sovereigns. While the bystanders scramble to pick up the gold, the dock inspector finds a hand of a dead woman buried underneath. To his absolute bewilderment, the next day, the cask has disappeared! Now it is up to Inspector Burnley of Scotland Yard to solve the mystery of the cask as well as the murder of the woman.