Can someone explain the key to me? *major spoilers*
I read the Wiki article's plot but I still don't understand the key—and I'm most likely mis-remembering some details.
It is a non-return key. So if the key is in the machine, the machine will not return to the time from whence it came.
At the beginning of the film, Wells has the key on his person, does he not? When Stevenson steals the machine, the machine returns to Wells's basement.
After Wells travels to the future, he keeps the key, again, on his person—one of the plot points that drive Stevenson's pursuit of Wells.
But if Wells has the key on his person in 1979—as he did in 1893—why does the machine remain in 1979? It's supposed to return back to 1893.
The whole movie I was confused by this. I get that the key and the diamond that keep the machine from vaporizing (sort of) are specific to this story's plot—without them, Wells can't go forward in time, and he can't kill Stevenson.
But the whole key thing seems more confusing than the actual time-traveling itself.