The Case of the Sleepwalker's Niece by Erle Stanley Gardner (Cassell, 1945)

Another find from the Lifeline Bookfair vintage table!  This is the first Australian edition of this book.  It's a very early paperback and a wartime publication, so it's in an austere utility format.  No exciting covers here!

There's also no blurb on this book, but there's really no need.  It's a Perry Mason story so we all know how it goes—Perry's client is arrested for murder, Perry locks horns with the police, Perry exposes the real killer at his client's trial.  However, there is a fascinating advertisement on the back which explains how the advertiser's product contributed to the War Effort: