Conversation so far:
When did A. J. Cronin start his writing career?
In 1930 at Dalchenna Farm by Loch Fyne A. J. Cronin was finally able to indulge his lifelong desire to write a novel.
What did A. J. Cronin write about at Dalchenna Farm?
A. J. Cronin composed Hatter's Castle in the span of three months.

Question: What was Hatter's Castle about?
Self-contained rewrite: What was Hatter's Castle by A. J. Cronin about?