100 Theme Challenge #16

(I published #17 by mistake yesterday...)

16. Night

Jogging at night was the best, really, because nobody was bugging Sean, or getting in his way. It was quiet except for his music, the streets well lit where he was running. He didn't notice the humming sound right away under his music, but then he felt it vibrate even through him. He removed an earpiece, tried to localize where it came from. He couldn't, it was from everywhere at once, it seemed. 

It was odd, but Sean continued his jogging, because he didn't want to waste his stamina. It was probably some construction truck or something making a lot more noise than necessary at this hour. He continued on multiple blocks, and got used to the buzzing sound. It was louder even than his music and wouldn't stop, only grew stronger as if its source was hot on his heels.

Sean realized that he wasn't jogging anymore – he was running away.

(What is 100TC?)