Themes might include historical truth vs. secrecy, the impact of the past on the present. Maybe Peter discovers a document or artifact that changes our understanding of history. Could there be a conflict with a secret society guarding the truth? That's a common trope, but maybe add a twist. Perhaps the history is not just about real events but includes elements of the supernatural or alternate reality.

Possible antagonist: A secret society that has protected the secret for centuries, or someone who wants to exploit the discovery. Maybe a university committee that's aware and is trying to stop Peter. Relationships could develop tensions between Peter's ambition and the risks involved.

Potential title ideas: Maybe use the actual Bodleian Library as a key location. The hidden project could be called something like "The Forgotten Chronicles" or "The Keepers of Oxford." The story should start with Peter receiving an anonymous letter or finding a clue. Build suspense through the research process, decoding old scripts, solving puzzles left by ancestors.

Themes could also touch on the ethics of revealing historical truths that might disrupt the current world. Maybe the secret involves a scientific invention or a historical cover-up. The tone should be intellectual, suspenseful, with some historical detail to ground it. Need to make sure the story has a balance between action and in-depth research, as Peter is a scholar.