This is a pretty interesting series, especially in light of the more recent poisoning of Sergei Novalny with the same Russian-developed nerve agent. However, Amazon Prime Video clearly states that Season 1 consists of four episodes and can be rented for $9.99. We rented it and only 3 of the 4 episodes would stream. The 4th episode will not load unless we sign up for a free 7-day trial of AMC. Even this may not be true. Wikipedia and IMDB list only 3 episodes in the first (and so far only) season of The Salisbury Poisonings. AMC's website indicates the fourth episode, but qualifies this with the word "UPGRADE," whatever that means. In any case, if you rent this series through Amazon Prime, be forewarned you will only receive access to 3 of the 4 episodes (despite Amazon's claim) and you will be left hanging with respect to the second and apparently even more problematic wave of poisonings that occurred in the Salisbury area. I think we'll asked Amazon to refund our rental charge here.