In listening to the song, I hear a 1-3-4-5 lick throughout the song. He moves that from key to key. Seems like I hear a 1-3-4-5 in the first part with a different beat. As you listen, you will pick it up. Check the song out on you tube. The 1-3-4-5 is 80% of the song. Hope that helps you get started. You'll be that far ahead when someone posts the bassline.