Well, a 'vanished novel' can be understood as a novel that has ceased to be accessible. There are numerous reasons for this. It could be that the author chose to withdraw it from circulation for personal reasons. Another possibility is that the publisher went out of business and the copies of the novel were not re - printed or distributed further, causing it to gradually vanish from the literary scene.
Since I don't have detailed knowledge of 'Vanished a Novel', it could be a thriller where a key item or a crucial witness vanishes, and the main character, who could be a detective or an ordinary person caught up in extraordinary circumstances, has to race against time to find out what happened before it's too late. There might be twists and turns involving different characters' motives and secrets that are gradually revealed as the story progresses.