The House that Seamus Built

Assignment's Unlimited receives a request from Seamus McBride, a speculative builder facing significant sabotage on his construction site in Borham Wood. McBride explains that someone has been systematically ruining his building materials and even poisoning his night watchmen. After investigating, it's revealed that two women, one of whom is Grace Bolton, have been sabotaging the site to prevent McBride from finishing the house, which sits atop hidden loot from a previous mail van robbery. The women, connected to the robber's family, aim to secure the treasure buried beneath the construction. The plot unfolds with the watchman uncovering the extent of the sabotage, leading to the capture of the saboteurs while exposing their desperate efforts to retrieve the hidden loot.