Ultimately directed by Meredith, it is based on the 1931 novel La Tête d'un homme (A Man's Head) by Belgian writer Georges Simenon featuring his detective Jules Maigret.

The nature of her husband's relationship becomes obvious to the wife, who taunts the mistress Edna that Kirby will have no money until his aunt dies, then leaves.

They leave, and when a patron there ostentatiously creates a row by ordering luxurious foods he cannot afford to pay for, the police are called; Maigret suspects it's an exhibition to frighten away Heurtin.

Legwork reveals that the diner, Johannes Radek, is a brilliant and educated young man suffering from manic depression.

Frightened back to the scene of the crime by Radek, Kirby shoots himself after being identified by Maigret, but gives up the letters MV before dying.

Finally, a clever ruse by Maigret sends a cornered Radek fleeing to the Eiffel Tower, which he begins to climb.

Radek prepares to dive spectacularly from near the top, but becomes crestfallen when Maigret feigns disinterest and starts descending in his elevator cart.