Q5: When do the detectives appear, sort of?

The last questions was answered three days ago, and no new question have been posted so I have one more for all you Tintinologists.

As you all know the Thompson twins chronological made their debut in Cigars of the pharaoh but later have a brief appearance in an earlier book when it was colored. Which book have their new "early" appearance?

Please be advised to post a new question in two days if your answer is correct.

Tintin au Congo, first frame.

Absolutely right, your turn to ask a question.

The detectives show up at the trainstation when Tintin is leaving for Congo. Their comment reveal that they don't actually know Tintin at this point.

SingingGandalf score a point to mr. mondrian please.

SingingGandalf score a point to mr. mondrian please

Sure, but you'll have to wait for the monthly update.
Interestingly (I say that word too often don't I), in the original black and white edition of Tintin in the Congo, it isn't Thomson and Thompson, but what look like 2 porters who we see in the first frame.