You’d think after thousands of years of exploring and mapping the earth that we’d know where everything is by now. Well, we don’t. Not even close. We’re going on a global quest to reveal the mislabeled, the mysterious and the just plain missing places off the map. We travel to Washington, D.C., to discover that the U.S. government has its own maps, and they reveal a very different country where top secret installations are connected by unmarked roads and underground tunnels. Then we head to San Francisco, California, as high-tech research vessels map the deep oceans and a scrappy group of DIY explorers launches ROVs from tiny inflatable rafts. Finally, we travel to China to the world’s second largest cave system, where a daring explorer plunges thousands of feet to map the depths.