August 12 Missing man found after nine days

I can't remember every word but it went something like this :

Thank you for meeting me, I know this must be traumatic for you, I can't tell you everything but I'll share what I can, you need to concentrate. Imagine you've a secret, one so big no one would believe you, even if you wanted to share it, unburden your self it would be no use. Now, with that in mind, consider how you would act if the only other person who knows the secret has just been killed. Not just killed, imagine if you have cleaved him in two with a sword but, and this bit is important, it was the right thing, the only thing you could have done. I know this is beyond you now, but trust me, this murder has saved lives, saved many more innocent lives than it took.
I'll be gone again soon, I just wanted to tell you this before I went.
Take this, it will explain more than I have, sorry for being so mysterious but you'll understand why soon enough.

And he handed me a bag and then got onto the train. As the engine started and the carriage began to pull out he appeared at the window, he seemed agitated and began to wave another bag at the window. I think he'd given me the wrong one. I opened the one I had and found it contained a sandwich and a bottle of water. Soon he was running towards the door, I kept losing sight of him as the train was packed with people looking for seats. We both ran but soon I had no platform left and the train by now was a blur. I don't know if he'll try to contact me again.