Perilous Siege

What is the Siege Perilous, and how does it affect the lives of everyone in the Regency universe of Pride & Prejudice?
When a man dressed in bizarre attire suddenly appears in a field on his Pemberley estate, Fitzwilliam Darcy has little inkling of the many and startling changes this man's strange arrival will have on his life, his family's lives, and indeed, his whole world.
Mysteriously sent to the Regency world of Pride and Prejudice, this refugee from a future Armageddon is befriended by Darcy. How will the presence of Major Edward McDunn infuence the events of Jane Austen's signature work, especially the tangled courtship between Darcy and the complex and endearing Elizabeth Bennet?