Dear Claire,

We’ve seen the unimaginably bright flash of ignition, so I only have a few seconds to write you this pointless postcard, which will surely turn to dust even if the time machine’s flux field deflects the nuclear blast around us. So I’ll just say this: they found us. Even the past is not safe from the invaders, and running to it will only further disrupt history. Already I fear we’ve destroyed the Hanseatic League. Stay away from Mohenjo-daro!

Sincerely,

Dr. Brown