One of the best parts of watching old science fiction serials from the 1930s are the strange title cards that come at the beginning of each installment to remind you about what happened in the last. This is a gallery of those titles from The Phantom Empire, a popular serial starring "singing cowboy" Gene Autry, who fights against the evil Queen Tika. She rules the underground scientific city Murania, which is "far advanced in the use of radio activity."
What's great is how the serial weaves together your basic scifi plot (discovering an advanced underground city ruled by an evil queen) with Autry's status as a radio star who does a daily program with some kids at Radio Ranch. So pop music is in peril as long as Queen Tika wants to get Radio Ranch away from the secret entrance to her city full of "radio activity." Get it? Radio and radio activity don't mix! Plus, an evil professor is also after Radio Ranch because he wants to harness the radium riches of Murania. Every episode usually features a song from Autry, as well as riding tricks from his teen pals in the "Thunder Riders," one of whom was famous for her rodeo skills. Cowboys, science fiction, and radio technology — the perfect combination! Luckily it's available on DVD.