This takes place immediately after the events of AC 3 and during SAO Alicization.
Prologue
The medical team rushed a body on a gurney to a helicopter. A man watched them load it into the helicopter.
"Careful now, we don't want to accidentally cause more damage. This man saved the world. Now it's up to us to save him." The man cautioned.
He climbed into the helicopter and sat next the the gurney as the chopper took off.
"It's an honor to meet you, Desmond Miles. I know you can't hear a word I'm saying but I feel I have to say this anyway. I'm neither an assassin, nor a templar. I'm not a part of your war. But the animus, it's like a low budget version of what my company, Rath, is making. I'm going to put you in a machine called the Soul Light Translator, or STL. The STL will take your fluctlights and begin to repair the damage to your brain, from both the solar flare and the animus. There's also someone you'll meet in there. I think the two of you will get along. Also, thank you for your help, even though you have no clue right now that you're helping us. The world thinks you're dead, Desmond. After you've recovered we'll help you start a new life. You can be free of this war." With that the man fell silent.
The helicopter neared the Ocean Turtle and the man smiled, the future was looking up.
Thanks for checking out the prologue of The Black Swordsman! Next time, Desmond is put in the STL and we see some familiar faces.