what we were much more straightfstraightf orward. we caught them. hoover wanted to send them right to jail. so the last one here had his secret letter writer. you have to read it, it's just -- the red says troops, nina, are coming to new york next week. so that's the secret writing, uncovered, these chilling messages. so here's one of the nazi spies to give an example of someone that was caught because he's a bermuda traffic. he was based in new york city, kurt ludwig, and so this is one of his mugshots here on the left. he was a nazi spy and he used pure met on. is in one heard of that? as common as aspirin. oftentimes people used dual use sick of writing in other words, medicine that could be both used for headache and for secret writing because when the fbi knocks on your door, that's just headache remedy. of course, when you find the toothpicks, you know, what are you writing, or even the letters themselves. i was amazed how many literacy wrote. i saw them in the finals. you should try it at home, to write secret messages, invisibly, for long pr