The appearance of two modern skeletons sparks "Five-O" to investigate murders ten years old.
This is a very interesting episode - tighty scripted, well-paced, the musical score is distinctive (rarely used in later episodes), and one of the few true "mysteries" where the viewer doesn't know the murderer until the end. Other good points include excellent acting turns by Herbert Lom and Jeff Corey as the artist who cannot stand to see McGarrett "despoil" a memory.
And memory is the key here. The memory of the beautiful and tragically killed Mrs. Mondrago is paramount to the entire episode. All characters bow to her full-length portrait, all spin rhapsodically about her beauty. This is the "high castle", and fairly typical of the time - women of "class" are objects of love but rarely have any other personal qualities or known abilities. It's quite moody and melancholy - but empty to many modern viewers. Personally, I like it as I like to see change in culture as reflected by the media of the time. As the daughter of the deceased Mrs. Mondrago who looks "exactly" like her, France Nuyen works in a fashion. In other words, she's beautiful and aloof and not much else is asked of her performance.
A classic and a niche episode at the same time, I wouldn't do without it. Seasons 2 through 6 really show the amazing versatility of "Hawaii Five-O" to its best effect.