Batman Beyond Season 3 Episode 30 The Duo Defy

Back in his iceberg headquarters, Mr. Freeze persuades the kidnapped Professor Isaacson to build him a thermodynamic ice ray beam. He issues an ultimatum that he will begin freezing the entire country if his demands are not met, then gives a demonstration of his weapon. As the villain works out just what his demands are, Batman and Robin track his seal, Isolde, through an ice-packed Gotham Harbor to locate the villain's hideout.