Back in the Victorian era, no-one had made the link between trains and murder, until July 1864, when a guard on a Hackney-bound train found blood in a first-class carriage, which in turn led to the discovery of a body on the embankment.
The victim was banker Thomas Briggs, and the story became a sensation as the public wondered whether this newfangled form of public transport was more dangerous than they had ever imagined.
Using original testimony drawn from court transcripts, newspaper reports, letters and memoirs, this docudrama recreates the case, and tries to get to the bottom of who exactly killed Mr Briggs.
But it turns out to be more than just a whodunit - the crime affected a cross section of London society, from the engine driver who found the body, to the detective who led the investigation.
BEST HIDDEN GEM Salvage Hunters (Quest, tomorrow, 9pm) | YOU may have thought that all those property and antique shows had taught people to be wary of throwing any period features in a skip and forgetting about them, but Drew Pritchard knows there are still hidden gems to be uncovered - if you know where to look.
He's the salvage hunter at the heart of this new series, and cameras follow him as he travels the country, finding scrap items his crack team of restorers can transform into treasure.
In the opening edition, he's hoping to turn a profit on a collection of 19th-century balconet rails, and also finds himself bartering with a baronet at one of the Scotland's grandest estates.
BEST PREDICTION Storyville: Google and the World Brain (BBC Four, tomorrow, 10pm) | WAY back in 1937, before anyone had thought of the internet, HG Wells predicted there would one day be a 'World Brain', a giant global library containing all human knowledge.
Seventy years later, it seemed his dream was coming true, as Google scanned the contents of millions of books into a specially created new website.
However, while some may have seen the project as a first step towards the higher intelligence Wells had prophesied, not everyone was so enthusiastic.
Over half the publications were still in copyright, prompting authors across the world to launch a campaign to stop the ambitious project.
This documentary follows the case all the way to the courtrooms of New York, and looks at the issues it raises about the benefits and dangers of the internet.
BEST NATURE River Monsters: Lethal Legends (ITV4, Wednesday, 9pm) | FOR a man aptly called Wade, it's little wonder Jeremy spends so much time paddling through water in search of weird and wonderful creatures for this show.
Whether travelling to the isolated jungles of Guyana, South America, or trekking around North America's vast waterways, this extreme angler just loves shedding light on assorted denizens of the deep for his show River Monsters.
Of course, movie-makers around the world are keen to exploit sub-aquatic creatures, and turn them into fearsome antagonists for B-movies such as Piranha and The Host.
In this show, Wade hopes to distinguish fact from fiction as he gets to the bottom of stories involving an underwater species with grasping hands that stalks children in Japan.
Jeremy also investigates the stories behind supposedly deadly freshwater creatures, including the legend of a lethal river spirit causing chaos on the Zambezi.
BEST GENEALOGY Meet the Izzards (BBC One, Wednesday, 9pm) | FORGET the time he ran 43 marathons in 51 days, comedian Eddie Izzard is about to embark on the most extraordinary journey of his life as he sets out to learn more about his roots.
a who of With the help of genetic experts and drawing on the latest scientific breakthroughs, he's using his own DNA to retrace his ancestors back 10,000 generations and nearly 200,000 years.
follow she No wonder the BBC have had to turn it into a two-parter showing on consecutive nights.
BEST GHOULS Being Human (BBC Three, tonight, 10pm) Meet 9p| OKAY, so the axe may have fallen on Being Human, and this series will be the last. But there are plenty of reasons to stay tuned to the end.
Nothing better demonstrates the tidy mix of comedy and drama that the supernatural show offers than the choice of guest stars this week - Julian Barratt of The Mighty Boosh and Ripper Street's Amanda Hale both lend their skills to proceedings as Tom runs into a charismatic werewolf by the name of Larry Chrysler, who has become a minor celebrity on the small screen, and Hal secretly arranges a meeting with Regency-era ghost Lady Mary.
Tom's new acquaintance rapidly becomes something of a mentor, but is he all he seems? And Hal's rendezvous ends up piquing Alex's curiosity, so she decides to follow him - but is surprised when she sees just how much she has in common with the old-fashioned spectre.