D'you really want to put an untrained civilian and a little boy in the line of fire, Sherlock? Because that's what this comes down to. I already got Jake shot through the stomach because of Caroline bloody Matthews. I'm not going to have it happen again. Not to Molly.

[John leaves off the tea and turns fully to face Sherlock, glaring up at him, even as he tries to slide around the point that the younger man is making.]