Maigret is called to Finland to help with a murder investigation because a suspect, Professor Duclos, is French and has demanded that someone representing the French police meet with him. Why is he a suspect? Konrad Porola is shot outside his home. Duclos is in the home and appears at a window looking toward the murder victim. And he's holding a gun which turns out to be the weapon used. Despite multiple red herrings it's clear to Maigret that the list of suspects is quite short, and it's more a matter of confirming who was where and when at the time of the murder. I'll say now that this story felt more like an Agatha Christie mystery in its plot, the intricacies of the murder, and with the resolution. I love this series, but I found this episode disappointing.
The book upon which this episode is based actually has Maigret going to Holland, not Finland. But this change in locale doesn't hurt the story and in fact fits better in the flow of prior episodes in this series. (Maigret had visited Finland in an earlier episode.) The town used in the film captures that in the book reasonably well, and it does matter since it's about knowing routes people took walking to and fro, location of buildings, and positioning of windows. Irina Björklund, playing the femme fatale, is the best part of the film. Her role is a crucial one and she does well.
Worth seeing? If you really like Maigret and you're working your way through all the Bruno Cremer series then yes, why not. But don't judge the series by this one film.