Agaton Sax suspects that an expert in an almost extinct language may be the brains behind a gang of international crooks with an interest in North Sea oil.
(Please note that this review is of the Swedish original, and not the very changed and edited English translation.) This book is, as you might know, the first part of a series. This is noticeable, especially (but not only) to people who are familiar with the series since before. It's slightly more grounded and realistic than the other books; most of the recurring characters have still not entered the scene, and the plot is a bit less well-structured than the later books (at least if my childhood memories can be trusted). The ending is a bit too dependent on a contrived coincidence. Still, this is more of an adventure story than a clue-based mystery, and as an adventure story, it's not at all bad, though a bit more dull than I'd like at times, and the plot does take a bit too long to get going.