Intriguing - Very interesting, especially because of being strange or mysterious

Jim found the study of physics very intriguing, because the more that was explained, the more seemed to be beyond comprehension - such as the origin of the universe.

Mary found learning sociology intriguing, because it seemed to answer many of her questions about society, but so many questions seemed unexplained.

The detective found that trying to solve who committed the robbery very intriguing because the clues pointed in so many directions.