Sherlock Holmes The Sussex Vampire

Sir - Our client, Mr. Robert Ferguson, has made an inquiry concerning VAMPIRES.  Since we are an engineering firm, unfortunately the matter is not one upon which we can advise. Perhaps you can HELP  

Holmes and Watson take on their strangest case yet when a distraught husband comes to them desperate to understand his wife's weird behavior.  He's caught her sucking the blood of their baby son! But there's no such thing as a vampire ... is there?