[Yes, this would be the point where Mycroft allows his smile to abruptly disappear, and his cold blue eyes go glacial as he take his umbrella up, gripping the handle as he steps towards the kidnapper.]

I do not trust you, sir. I do not trust you as far as I could conceivably throw you. So let me make this clear - if I hand you this satchel of money, and I find out that Lestrade has anything more than a mild skin irritation? I will find you. I will find each and every last one of you. I will find your families. I will find your friends. I will unearth every enemy you have, every person you have ever owed a single shilling to. I will raze the earth around you, and leave you in the ashes.

[He took another step forward, his voice as frozen as his expression.] Trust in that, and show me Lestrade. Now.