Complex sentence: When he gets on the Skyway, the Young Man tells Calder that the bomb is in his radio but he must not throw it away because it will explode on impact, and the paths below the Skyway are crowded with patrons.
Split into simpler sentences: When he gets on the Skyway, the Young Man tells Calder that the bomb is in his radio. He warns Calder not to throw it away, because it will explode on impact, and the paths below the Skyway are crowded with patrons.