Hollywood legend Cary Grant first tried LSD in 1958 in the office of Dr Mortimer Hartman, and would later claim it saved his life

At the peak of his fame as one of Hollywood's leading men, yet plagued with self doubt, Cary Grant discovered a new drug which changed his life forever.

The British-born actor would soon be loudly proclaiming his love for LSD, a substance he first took as part of a controversial treatment programme at the age of 53.

He once famously recounted that one trip left him feeling like a 'giant penis launching off the Earth like a spaceship'.

Grant's relationship with the drug, which he first tried in his therapist's office in 1957, forms the basis of a new documentary set to screen at the Cannes film festival next week.

The North By Northwest actor, remembered as one of Hollywood's greats, is the subject of feature Becoming Cary Grant.

Focusing on the period between 1958 and 1961, it details Grant's life through the kaleidoscope of an estimated 100 acid sessions.

Grant, pictured in 1959 classic North By Northwest, was convinced that taking acid could help keep his insecurities at bay

The documentary features home video footage from the star, and extracts from his unpublished autobiography

Movie director Mark Kidel told The Guardian: 'He claimed he was saved by LSD. You have to remember that Cary was a private man'

Producer Nick Ware told The Guardian: 'Like all documentary makers, we started out looking at the construction of Cary Grant. But we ended up deconstructing him through the LSD sessions.'

Grant was a patient of Dr Mortimer Hartman, who diagnosed him with 'prolonged emotional detachment', and thought he could help cure, Vice reports.

Grant, by that time divorced three times, first tried LSD in 1958 in the doctor's office.

Movie director Mark Kidel told The Guardian: 'He claimed he was saved by LSD. You have to remember that Cary was a private man.

'He rarely gave interviews. And yet, after taking acid, he personally contacted Good Housekeeping magazine and said: "I want to tell the world about this. It has changed my life. Everyone’s got to take it."'

Born Archie Leach, Grant believed his mother had died when he was a child, only to discover when he was in his 30s that she had in fact been committed to the Bristol Lunatic Asylum by his father

The movie uses the star's own words from his unpublished autobiography, spoken by actor Jonathan Pryce, and newly discovered personal footage he shot to reveal more about the man who was born Archibald Leach in Bristol, England, in 1904.

Born Archie Leach, he believed his mother had died when he was a child, only to discover when he was in his 30s that she had in fact been committed to the Bristol Lunatic Asylum by his father.

Reflecting on his early exposure to LSD, Grant wrote: 'Any man who experiments with something that cannot benefit himself, or add to his happiness, and that of his fellow man in turn, is a fool and a menace to society.

Grant pictured with fourth wife Dyan Cannon and daughter Jennifer. Cannon would later say he believed LSD gave him 'a path to truth and enlightenment'

'I’ve heard that a man here and there died during LSD25 sessions; but then I’ve heard that men died during poker games and while watching horse racing; but that didn’t seem to stop such occupations.'

And he continued: 'In attempting to traverse the next step into progress and knowledge, men have always died.

'But there is a difference between the man who knows what he’s about with a high-powered airplane, and an idiot who puts wings on a bicycle and takes off from the edge of Niagra Falls.'

He would state that LSD brought the subconscious to the fore, and wrote he later regretted the 'ignorance' he had previously lived in.

'The shock of each revelation brings with it an anguish of sadness for what was not known before in the wasted years of ignorance and, at the same time, an ecstasy of joy at being freed from the shackles of such ignorance,' he wrote.

Despite being at the height of his powers, Grant would quit making movies in 1966 - the same year possessing the drug became illegal in the US.

Despite seemingly going quiet about LSD in the later years of his life, he left a sizeable sum to Dr Hartman.

The new documentary explores the Hollywood legend's relationship with LSD

Grant, pictured in 1964 movie Father Goose alongside Leslie Caron, was an outspoken advocate for LSD, which he felt everyone should try

His fourth wife, Dyan Cannon, recounted in 2011: 'Cary claimed LSD offered a path to truth and enlightenment, and his tactics to persuade me to try it were rather underhand.

'On a trip to London in 1963, we had an unexpected visitor. Cary had apparently decided that the time was right for my first "cosmic exploration" and I came into the sitting room of our rented house to find that his acid guru, Dr Mortimer Hartman, had been flown over from LA to guide me through it.

'"It’s like leaping off the high dive," Cary told me when I complained about being ambushed in this way. "If you take too much time to think about it, you’ll back out."'