#7 - The Day of Uniting by Edgar Wallace (1930)

dustjackets.com

About this edition: This is one of five titles released simultaneously in a Christmas boxed set. These are the only five titles appearing in the green cloth binding.

Edgar Wallace (photo: wikipedia)

About the author: Here is a Wikipedia article on Edgar Wallace. He also authored The Hand of Power in the Mystery League series.

Major characters: 

• Jimmy Blake, 27, wealthy happy-go-lucky war ace
• Gerald Van Roon, Jimmy's cousin, roommate, and scientist
• Joe Sennett, foreman at Ponters Ltd.
• Delia Sennett, Joe's daughter
• Tom Elmers, employee at Ponters Ltd.
• John Stamford Chapelle, Prime Minister of England
• John Stope-Kendrick, Secretary of State
• Walter Maggerson, mathematician and explorer
• Lord Harry Weltman, Minister of Defence
• Tyrhitt Palythorpe, ex-con, printer of Spice, a scandal sheet

Locale: England

Synopsis: Ponter's Ltd. is a commercial print shop, specializing in scientific texts. They also have a contract to printing government documents. One night foreman Joe Sennett catches Tom Elmers fooling around with the type.  It is found that someone is sabotaging the books being printed by inserting erroneous or nonsense text after the proofs have been approved. Highly embarrassing. 

Jimmy Blake, wealthy happy go lucky war ace, meets and is taken with Delia Sennett; daughter of foreman Joe Sennett. Blake gets an invite from his lodger, Gerald Van Roon, to a dinner of scientific types hosted by Prime Minister Chapelle. At the dinner, explorer Walter Maggerson staggers in begging the PM to stop "The Terror" (but no one knows what "The Terror" is).

Tyrhitt Palythorpe, ex-con and printer of a seamy scandal sheet, tries to lure Tom Elmers away to work for him. 

One night Gerald Van Roon is called away, and is soon found dead on the nearby heath. Soon John Stop-Kendrick dies also by his own hand, while running from "The Terror".

Whatever "The Terror" is, it is the main focus of a group of officials who meet at night in a vacant building and engage in a frenzy of activity to stop it.