[John glances over his shoulder and up at Sherlock disapprovingly.]

I dunno much about it. He claimed it was rigged to an abandoned carriage I was trapped in with him. Pressure trigger. There was a briefcase in the carriage that had a code we supposedly needed to disarm it. He gave us, uh... some kind of clue. Sherlock looked into it, but it didn't make much sense.

I assume you found Caroline's body down there? She was dead in the carriage, sitting with Jim when I got there.