The melody of Radioactive by Imagine Dragons runs 314 notes across 44 bars, 2:30 long in Bm at 136 beats per minute. The tab sits low on the neck, mostly under the fourth fret, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? Radioactive chords and lyrics.