When he gets his second scar he's in England - in London to be exact, because that's just his luck. He's not there normally, just for this one day, after begging his Cêpan for weeks to let him go.
Eight supposes that this is just proof that his Cêpan was right, not that he wants to admit it.
London, being London, is so busy and crowded that both he and his Cêpan panic as they try to get him somewhere quiet, before the light starts glowing and before he starts screaming.
The best they can manage is a McDonald's toilet, where the light doesn't matter and he has to bite on his lip until he draws blood to stop the screams.