There was no way Claire could have ended up there by herself because the subway station was nowhere near close enough to walk to from here. That plus the fact that she hadn't been reachable by phone was highly suspicious.
If Ethan had to guess, she had been taken somewhere by force. He immediately sent the location to Alex. Feeling restless and unsure what else to do, he ended up going back to Belmont. There was no way he would be able to concentrate on video games with his mother missing so he may as well help Karli keep an eye on the kids.
Besides, he wanted to have Emma within his sight right now for a reason he couldn't fully explain. He had a bad feeling about all of this.
If someone had taken Claire…who would do that? And why? He knew that her relatives put a hit out on her and that led to her meeting Alex but that was years ago! Why would they bother coming after her again now?