You know it’s serious when Mluleki Ntsabo isn’t smiling. The South African Broadcasting Corporation commentator is small in stature and huge in energy, beaming a high-wattage grin as he booms away in English on the main mics or Xhosa on the update line. But as I walked into the broadcast area on the third afternoon of the Cape Town Test in March 2018, he came bouncing round the doorway behind me like a rubber ball, rebounding off the far wall, his face stern as he rushed along. “Did you see?” he asked with urgency. “Cameron Bancroft has something on the ball.”

We piled into our commentary box where the ABC and SABC were running a joint broadcast. On the gantry outside our window were the three lead Supersport camera operators, adjusting and aiming their artillery-sized lenses, making fine calibrations beyond our understanding. They were chattering away on their walkie-talkies, coordinating with the other cameras all around the ground. There were close to 30 cameras overall, each with a part to play.

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It was Bancroft they had followed first, tipped off to the possibility of shenanigans and tracking his every movement with or without the ball in hand. An hour or so later, they had the shot. Cricket lenses have 76× to 95× zoom, able to shoot from the grandstand to track a single bead of sweat running down a batsman’s face. “Through this extensive framing latitude, every dramatic on-site sensation can be captured,” is how Canon describes it. Too true. Bancroft was holding the ball in his left hand, scrubbing his cupped right palm and fingers over the leather as though battling an unforgiving doorknob. You could see the pressure he was applying by the white flush of his knuckles. The fix was on.

But the broadcasters wanted more. Something explicit. What better way than to have the suspect provide it? So they sat on the original footage for a few minutes, setting up the cameras. One for the coach, Darren Lehmann, watching from a Rapunzel window up in the team rooms. One for the reserve player, Peter Handscomb, surrounded by discarded pads and gloves down at the side of the field. Cameras on the captain, vice-captain, umpires, and half a dozen on Bancroft himself. Then the final ambush: just after Pat Cummins had finished a spell in the 42nd over, the original close-up of Bancroft’s scrubbing hand flashed on to the ground’s big screens.

The Australians poked their heads into the trap immediately. Lehmann made a radio call to Handscomb, who trotted on to the field and spoke to Bancroft. The young fieldsman, heart plunging through his shoes, already knew exactly what was going on. Meanwhile, third umpire Ian Gould was watching television monitors and jumping on his own walkie-talkie from up in the grandstand, prompting on-field umpires Richard Illingworth and Nigel Llong to wander over to each other for a chat. So Bancroft did what any kid shoplifting a Milky Way would do: he shoved the evidence down his pants.

Most apprentice petty thieves don’t have quite the same battery of surveillance devices awaiting their every move. The initial footage was replaying as the umpires moved over to Bancroft. He produced the soft black bag for his sunglasses, claiming that was all he had in his pocket. Strictly speaking this was true. Sandpaper in the jocks, though, was about to cause more discomfort than the immediately physical.

The second lot of footage hit the screen: the long shot of Bancroft watching the umpires coming together, then turning his back to them. Cut to the close-up, and the super slow-motion capture of the waistband pop: this camera that usually depicts the vibrations in a cricket bat at the moment of impact, or the faintest twitch of glove on ball, was instead capturing 150 frames a second of a drawstring being tugged, frantically enough to turn the slow version into an incongruously extravagant flourish. A magician’s fling of the hand, the cord springing out, two ends separating, then trailing, trailing, the smoke coils of downed aircraft. The magician in his haste proved to have no magic at all; not the slightest hint of sleight of hand in the way he took a bright yellow square from his pocket, thoroughly unpalmed, and pushed its incriminating colour into hiding.

It was a confession, signed unwittingly but indelibly. Yet, as obvious as it was, it was hard to believe. It was hard to believe it could have been so obvious.

There is a human tendency at events of significance to gather, to legitimise our experience together. We can’t risk some spectacular misinterpretation; we look to others to confirm a city burning before our eyes. So commentators from every television and radio station crammed into the small break room in the broadcast centre. The previous morning its lone occupant had been Shane Warne, face down among some errant cables to take advantage of a break, snuffling awake with an imprint of the industrial grey carpet mottling one cheek. Today, though, everyone who wasn’t on air was crowded in here: Shaun Pollock, Allan Border, Jim Maxwell, Kepler Wessels, Brendon Julian, arrayed around the widescreen television to watch the footage repeat and repeat.

There was no doubt or defence in the slow-motion ballet of elastic. As we watched, another shot was shown with even more detail. Bancroft’s hand on the ball, close-up on his fingers. Index and middle knuckles parting for a second, for a millimetre, an aperture just enough for the camera’s aperture to swoop through. A frozen flash of yellow proving beyond equivocation that his hidden treasure had been applied to the ball.

Admittedly, it can seem absurd to imbue this action with such drama. But altering a ball can alter the course of a match, the worth of a legacy, the history of the game. This ball would alter some of the world’s most prominent careers.

Facebook Twitter Pinterest Steve Smith, flanked by Cameron Bancroft, admits to ball tampering during the third Test against South Africa. Photograph: AFP/Getty Images

Ball-tampering has always been a dark art. Bowling teams try to manage their sole weapon into its most dangerous state, but use methods retaining some vestige of deniability, or at least the mitigation of spontaneity. To use foreign objects brought on to the field for that purpose was something else. No Australian player had ever been charged with tampering, and now came a case that wasn’t even marginal. This was proper cheating. To be caught so fully, so squarely, and looking so amateur in the attempt, just capped it off. And if we knew anything, it was that the least-experienced player in a team wouldn’t develop that plan on behalf of 10 colleagues of his own accord. This story was going to be huge.

Back on the gantry, the cameramen were high-fiving each other at the sting. Supersport’s TV director leaned back in one of the hinged chairs set outside, swinging back and forth in contentment with his arms crossed and a toasty smile. “Our guys did a very good job today,” he said in his thick Afrikaans pronunciation, all plosives and alveolar trills. “A very good job.”

When the bust happened the match had been poised. South Africa’s star batsman AB de Villiers was at the crease. His team was 175 in front in their second innings, and two wickets down, but Australia’s pace leader Mitchell Starc had induced two collapses in the opening Test of the series with reverse swing. The ball had just been thrown to Starc for a new spell, and was in the reverse-swing hotspot at 43 overs old.

Once the subterfuge became bloody-obvious-fuge, the Australians had to suffer through another session of play. Faces were glum and minds distracted. Smith spent time off the field: who was he speaking to? What did he know? Was strategy afoot, or was he curled up in a toilet stall? David Warner filled in as captain, calling a video review to dismiss Faf du Plessis. Warner wouldn’t be implicated that day but would be central later. Handscomb filled in at slip, taking a catch. He had been implicated but would later be cleared. One other wicket fell, taking the total to five, the match slipping away by stumps with De Villiers still there and the lead at 294.

But the score was no longer a big factor in Australia’s glumness as they left the field. They knew the trouble that had been circling was coming in to land. The standard radio and television interviews were denied, at least by their side. South Africa’s opener Aiden Markram, who had been batting with De Villiers when the trap was sprung, used his 23 years of age to play a very straight bat as I interviewed him for ABC: “As a batter you’re in your own zone and your own tunnel vision. I wasn’t aware of it at all. I wasn’t even aware of it as I got out. I’ve not been exposed much to it. I haven’t played many first-class games, and haven’t played much Test cricket. I’m still very young and naive in things like these, and I think it may be a blessing in disguise.”

He took the same tack with the press conference that followed, speaking at length to a full room. But the room wanted the other team’s young opener: Bancroft in his eighth Test. The question was whether it might also be his last. Markram wrapped up and still there was no sign from Australia. There had been a message that someone would show. So we waited. Twenty minutes, half an hour, three-quarters. From the full-length windows on the fourth floor of the North Stand, Cape Town’s sky fell away into darkness, the seemingly immutable bulk of Table Mountain dissolving, the cricket ground vanishing until all that was left were our own reflections coming back at us in a blaze of light.

After nearly an hour there was movement on the far side of the ground. You had to stand up against the glass to see through the glare. Distant figures came down the steps, then on to the grass. As they crossed the oval we could make out two white-clad forms, Bancroft and Smith still in their playing gear. On their right was the media manager, Kate Hutchison, hands in her jumper pockets as she hunched forward. On the left, the team manager, Gavin Dovey, in a grey suit. Trailing him was the security manager, Frank Dimasi, his long peaked hood pulled over his head. Shoulders were rounded and feet slow. From outside, the press box windows high in the grandstand were glowing gold, but those approaching would have felt little warmth or welcome.

• This is an edited extract from Steve Smith’s Men by Geoff Lemon published by Hardie Grant Books, RRP £16.99 (UK) and $29.99 (Australia). It is available now in Australia and from 13 December in the UK