There are three people you need to know about. You need to know about them now because the man telling you about them won't be here for long, and these are dangerous people. You're the only one who can stop them. Listen.
Time travel is possible. Traveling into the future can be done -- but only one day ahead of the present. Some sort of strange law of the universe makes its impossible to leap ahead more than a single day. Another law of the universe is that it's impossible to change the future events once you return... things have to play out as you've seen them, or else you couldn't have seen them in the future. You've got to simply watch things go as you know they must go.
The man who's speaking to you has seen some unplesant things. He realizes now that the future isn't something people need to see. Once you see it, it can't be changed, and so having seen it becomes useless. You can see what will happen to you tomorrow, but no matter how awful it may be you can't stop it.
"You'll forgive me if I sound a little confused occasionally, I have so many things to remember and so little time to remember them all." - the man who speaks to you