Marnie Novak is the mother of the villain Lorelei von Leyden, whom she hires to steal the Cyan wolf for her in Ruby Redfort, Catch Your Death. Lorelei does not know that Marnie is her mother, and believes her mother died when she was a baby. The full truth on this matter, however, is not told in any of the existing Ruby Redfort books. She is Australian, as is shown by her accent.
In the third book, 'Catch your death', Novak hires her daughter Lorelei to steal the Cyan wolf for her, which she needs for the purpose of extracting its irresistible scent for a currently unknown reason (although we know she did not want to make money out of it like Lorelei did). She sends Lorelei coded instructions in the form of scented paper as she travels to Twinford.
After Ruby releases the Cyan wolf and Lorelei flees her mountain cabin, Mrs. von Leyden arrives at the cabin and kills Lorelei's assistant Eduardo after he admits that Lorelei has stolen some of the Cyan scent, which Ruby had taken. Mrs. Von Leyden then pursues Ruby in her caravan, and after getting her to hand over the Cyan scent backs Ruby off a cliff and then lights a fire. She leaves with the Cyan scent. It is unknown what she does with it, but it is supposed that she delivered it to her 'client'.
in the fifth book 'Pick your poison' it is revealed that she works with the count for someone else that is never revealed in the existing book who later turns out to be Casey Morgan.
In the final book, it is revealed that she was an actress who worked for the Count but her career was cut short when she had Lorelei. She became bitter and blamed it all on Lorelei.
After chasing after Ruby and indirectly causing the death of Bradley Baker, Marnie is pushed backwards by Bug (Ruby's dog) and falls into a gap in the ice. According to the book, she is "not found until spring". She presumably dies of hypothermia and/or drowning.