The Mercy tells the true story of the amateur sailor Donald Crowhurst (Firth) who participated in a 1968 Sunday Times competition to single-handedly circumnavigate the world's oceans via yacht.
Crowhurst kept logs while at sea, writing over 25,000 words of varying trustworthiness about his wildly dangerous solo voyage. Hoping to win the cash prize and save his failing business, Crowhurst slowly suffered a mental breakdown at sea. Things, alas, did not end well.
Weisz, meanwhile, stars as Crowhurst's waiting wife Clare.
James Marsh, who won an Academy Award® for his work on Man On Wire (2008) and most recently directed The Theory Of Everything (2014), is behind the camera on this one. Given Firth, Weisz and Marsh have all got Academy Awards on their mantlepieces, we wouldn't be surprised if this gets mentioned in next year's awards chatter.