The bald guy pulls out something that looks like a flattened sphere. He thumbs a switch in the center of the thing, then drops it.
"Sorry folks," he says with a sneer. "No witnesses."
On his left wrist is some kind of oversized digital watch. He fiddles with it for a few seconds. A blue light comes over him, and the atoms of his body scatter away like grains of sand blown by the wind.
A stunned moment of silence. The flattened sphere beeps once, twice, then three times rapidly.
The coffeeshop, and everything else within 100 yards, is completely vaporized.
Needless to say, but it has to be said: you are dead.