The Calculus Affair (1956) or "how scientific inventions can serve humanity without being coveted by military powers", in the tense climate of the Cold War.

This new adventure takes Tintin back to Syldavia and Borduria.

After inventing an ultrasound machine, Professor Calculus is kidnapped.

Jolyon Wagg, an insurance sales rep, makes his entrance in this story, and will prove to be a constant nuisance.

A thrilling chase, surprises, old friends getting back together, headlong fights ... all this for a stake in what seems to be limited to an ordinary umbrella.

This is probably the most "detective-like" story.