In the novel Dead Man's Folly, Superintendent Baldwin is a Police Officer at the Helmmouth Police. He is described as being a "large comfortable-looking man".
During the investigation into the events at Nasse House his men found the hat of Hattie Stubbs presumably in the river Helm near Helmmouth. Baldwin later supervised the search of Etienne de Sousa's yacht the Espérance moored at Helmmouth. The search did not reveal any leads about the whereabouts of the missing Lady Stubbs.
Superintendent Baldwin also consulted Otterweight, to find out what would have been likely to happen to a body if it had been dumped into the river Helm.