PrimeWire

You can now watch the entire History's Greatest Mysteries Season 6 Episode 3 movie online in high-definition quality, complete with English subtitles for a better viewing experience. Best of all, there’s no need to download anything—simply stream it directly from your device anytime, anywhere.

On February 14th, 1929, one of the most shocking murders in mob history goes down in Chicago--and becomes known as the Valentine's Day Massacre. The 20s and 30s are full of gangland murders, but the Valentine's Day Massacre is considered the most brutal -- and the toughest to solve. So who carried out the Valentine's Day Massacre? And why?