This is an exceptional documentary covering a series of archaeological excavations between 2014 and 2018 that aimed to trace the quarry of the Stonehenge bluestones. While the stones' origin in the Wels Preseli Hills was suspected for a century, pinpointing the precise location seemed a long shot. The actual discovery and dating of the Neolithic quarry was an exceptional achievement, but it further led to the revelation that the stones were extracted four centuries earlier than their arrival at Stonehenge and thus could have been set up in a separate monument in the intervening period. Further excavations in the region were undertaken to find the location of this lost site and the evidence for its connection with the Stonehenge bluestones.
The way this journey was presented is a great example of the high standard of quality characteristic for BBC documentaries. It collects footage from multiple video diaries recorded over the many excavation seasons and builds a consistent narrative, documenting the progress of the search, the highs and lows and the methods applied. Many of these are cutting edge like photogrammetry, stimulated optical luminescence or magnetometry. Others are more familiar like radiocarbon dating of organic remains or uranium-lead dating of zircon crystals. Combining the video of these lab based techniques with the dig site diaries of the excavation work under the unforgiving weather creates a good cross-section of modern archaeology.
And finally this multi-year campaign is woven into an engaging narrative by the presenter Alice Roberts lending the show her irresistible enthusiasm for the subject. All in all this documentary is a great overview of a major recent discovery together with a snapshot of how archaeology is done today.