When the first trailer for 28 Years Later was released last year, fans were immediately struck by the theme of sheer terror that ran through it.
And part of what made it so scary was its use of a 1915 recording of one of Rudyard Kipling's lesser-known poems.
The rendition of Boots by American actor Taylor Holmes sends a chill down the spine of anyone who listens to it - a fact that explains why it has featured for decades in the US Navy's training programme.
Last week, it received more exposure with the release of Danny Boyle's 28 Years Later.
It reveals what has become of Britain nearly three decades on from the outbreak of the 'Rage Virus' first seen in 2002 film 28 Days Later.
Holmes' Boots recording is played at the start of the film, when Jamie and his son Spike - played by Arron Taylor-Johnson and Alfie Williams - arrive on mainland Britain after leaving the sanctuary of the virus-free island of Lindisfarne.
Reflecting the repetitive actions and thoughts of a British soldier marching in South Africa during the Boer War, Kipling's poem was published in 1903 - the year after the conflict had ended.
It builds from a calm, monotonous repetition of 'boot, boot, boot, boot', to a crescendo of screaming.
The final verses include a plea to 'keep from goin' lunatic' and the poem ends with the words: 'There's no discharge in the war!'
We're foot -- slog -- slog -- slog -- sloggin' over Africa
Foot -- foot -- foot -- foot -- sloggin' over Africa --
(Boots -- boots -- boots -- boots -- movin' up and down again!)
There's no discharge in the war!
Seven -- six -- eleven -- five -- nine-an'-twenty mile to-day
Four -- eleven -- seventeen -- thirty-two the day before --
(Boots -- boots -- boots -- boots -- movin' up and down again!)
There's no discharge in the war!
Don't -- don't -- don't -- don't -- look at what's in front of you.
(Boots -- boots -- boots -- boots -- movin' up an' down again);
Men -- men -- men -- men -- men go mad with watchin' em,
An' there's no discharge in the war!
Count -- count -- count -- count -- the bullets in the bandoliers.
If -- your -- eyes -- drop -- they will get atop o' you!
(Boots -- boots -- boots -- boots -- movin' up and down again) --
There's no discharge in the war!
We -- can -- stick -- out -- 'unger, thirst, an’ weariness,
But -- not -- not -- not -- not the chronic sight of ‘em,
Boot -- boots -- boots -- boots -- movin’ up an’ down again,
An’ there’s no discharge in the war!
’Taint -- so -- bad -- by -- day because o’ company,
But night -- brings -- long -- strings -- o’ forty thousand million
Boots -- boots -- boots -- boots -- movin’ up an’ down again.
There’s no discharge in the war!
I -- ’ave -- marched -- six -- weeks in ’Ell an’ certify
It -- is -- not -- fire -- devils, dark, or anything,
But boots -- boots -- boots -- boots -- movin’ up an’ down again,
An’ there’s no discharge in the war!
Try -- try -- try -- try -- to think o’ something different
Oh -- my -- God -- keep -- me from goin’ lunatic!
(Boots -- boots -- boots -- boots -- movin’ up an’ down again!)
There’s no discharge in the war!
When Kipling wrote the poem, the loss of more than 20,000 British troops was still very fresh in the memory.
The poem's precise metre - the first four words of each line are read at a rate of two per second - matched the time to which soldiers marched.
American actor Holmes, who died in 1959, appeared in more than 100 Broadway plays.
His delivery in the 1915 recording begins relatively measured, but then ramps up to wild, terrifying abandon.
For decades, it has been used in the US Navy's Survival, Evasion, Resistance and Escape (SERE) course.
Recruits are subjected to it as part of efforts to put them under pressure.
Former naval aviator Ward Carroll previously said: 'Anyone who has ever attended the US Navy's Survival, Evasion, Resistance and Escape (SERE) school will never forget the poem.'
Holmes' rendition was also used last year in the marketing campaign for video game Call of Duty: Black Ops 6.
Fellow British poet T.S. Eliot chose to include Boots in his 1941 collection A Choice of Kipling's Verse.
For every year from an initial holiday in 1898, Kipling visited South Africa.
The author wrote several poems to support the British cause in the Boer War.
Britain won the conflict but more than 20,000 British troops were killed.
Kipling's most famous works include The Jungle Book and his Just So stories.
His 1910 poem If also remains hugely well-known.
The author died in 1936 aged 70.
He was left bereft after his son Jack was killed in the First World War.
The first trailer for 28 Years Later was released last December.
It sparked a flurry of publicity in large part because of the appearance of what appeared to be a zombified Cillian Murphy, who starred as lead character Jim in 28 Days Later.
However, it later emerged that the figure was not Murphy but art dealer Angus Neill, who was given a part as an extra by Boyle after being talent-spotted.
Murphy, 49, is though an executive producer on the new film and is set to star in upcoming sequel 28 Years Later: The Bone Temple.
The Mail's Brian Viner gave the new film five stars in his review.
He wrote: 'With the terrifying and electrifying 28 Years Later, director Danny Boyle and writer Alex Garland have delivered the best post-apocalyptic survivalist horror-thriller film I have ever seen.'
'Which sounds like limited praise, yet it's a much more crowded field than you might think.'
'Boyle also made the 2002 film 28 Days Later, setting up the story (written by Garland) of a terrible virus rampaging through Britain, which in those days was more the stuff of science-fiction than it seems now.'
Reflecting the repetitive actions and thoughts of a British soldier marching in South Africa during the Boer War, Kipling's poem was published in 1903 - the year after the conflict had ended.
British troops seen aboard Cunard liner SS Catalonia as they arrive in South Africa during the Boer War, 1899
The figure that fans believed was a zombified Cillian Murphy. It later emerged that the figure was not Murphy but art dealer Angus Neill, who was given a part as an extra by Boyle after being talent-spotted
'There was a sequel, 28 Weeks Later (2007), but that had a different director and writer.'
'Now, Boyle and Garland have reunited to mighty effect.'
'There’s no need to have seen the first two films - this one stands alone.'
Boyle's original film famously showed Murphy's character walking through a deserted London after waking up from a coma in hospital.
The director opened up earlier this month about how the scenes were shot.
Admitting the crew did not have the money to be able to afford to formally close the road, he said that he instead enlisted his daughter to help.
He told The Times: 'We didn't have the money to close the bridge, but had a plan to be there at 4am.'
'The police can't ask the traffic to stop, but they will allow you to ask drivers.'
'So we hired a lot of girls, including my own daughter, who was 18.'
'Anybody driving at that time is a bloke, so we had the girls lean in, saying, "Do you mind?" And it worked fine.'