What genre is this?

So I am learning how to prepare a query letter for my novel, it's a historical romance with a mystery subplot that basically guides the plot while the protagonists are in love and kiss and like full on romance while solving it so they can end up together.

So in my query letter's hook do I write it as historical romance novel set against the backdrop of (the time period) moving back and forth between (like the setting) to solve a murder mystery.