In late September of 2022, the Nord Stream 1 and 2 pipelines — which supply Russian natural gas to Germany and the rest of Europe via the Baltic Sea — were hit by a series of underwater explosions. Against the backdrop of Russia's invasion of Ukraine and the ongoing tensions that have resulted, officials soon concluded that it was an act of intentional sabotage. But by whom? More than half a year later, there's still no clear answer. Today, Washington Post reporter Shane Harris takes us inside this high-stakes whodunnit, explaining the various theories, and the evidence supporting or undercutting them — and how it all hinges on an unassuming 50-foot sailing yacht known as the Andromeda. For transcripts of this series, please visit: https://www.cbc.ca/radio/frontburner/transcripts