Brothers Harlem and Piri Kirton started the night that would change not only their own lives but those of many others by watching the movie American Gangster.

By the time they met up with Ruamoko Taiapa and Jono Wilson later on January 15, 2008 they were heading for a night of random violence.

Prosecutor Sarah Mandeno told the Auckland District Court this week the young men were bored, had no money and were "cruising for trouble".

Witnesses said they had spoken of committing a street robbery and Taiapa was even heard to say they were "up to no good".

At 1am they came across Daniel Swafford, biking alone along Taharoto Rd. Piri Kirton, the youngest of the group, was driving the car that swerved in front of Mr Swafford. Wilson got out and chased him, landing a punch in the head before the cyclist could escape.

From there the group went to the Milford Beach carpark. Again it was Wilson who acted first, getting out and approaching a young Russian couple, Denis Khotchenko and Valeriya Nesterova.

Mr Khotchenko said Wilson asked for a beer before the conversation took a sinister twist when Wilson leaned close to the open car window and said, "Have you ever met a real gangster".

What followed was a brutal assault that left the young couple bloodied and broken. They were both struck with iron bars that made them fear for their lives and left them unconscious.

As Mr Khotchenko slumped in the sand, Ms Nesterova was dragged from the car. Someone tried to remove her pants but only her belt was taken off.

Ms Nesterova fled, leaping into an inlet and swimming across it to get help, while her dazed boyfriend woke up and found her gone, the attackers gone and "blood everywhere".

They both eventually found help and were reunited at North Shore Hospital. Mr Khotchenko had his front teeth smashed out and bleeding on the brain, Ms Nesterova suffered multiple skull fractures and major lacerations, a broken finger and severe bruising.

All the attackers escaped with was a cellphone, some keys and a box of Export Gold beers.

But the violence didn't end there. At 3.45am Oskar Carroll and Ericka Rancourt were walking on Lake Rd. The group pulled over next to them and the metal bars came out.

Within seconds a second couple were on the ground, bleeding heavily from head wounds. Ms Rancourt's handbag was taken.

She later told police she thought she'd been hit by a car.

She's grateful she doesn't remember anything and has been spared having nightmares about the ordeal.

"In some ways it was good that it happened. I met my boyfriend Matt and it has given me the opportunity to do things, like focus on school."

Later that morning Taiapa went home. He woke his mother, Kiriana Jan Taiapa, and told her what had gone on during the night.

Later that day they were driving to a house in Glenfield when he told her the weapons used in the attack - a wheel brace and two 30cm metal bars - were under the rear seat on the driver's side of the car wrapped in a T-shirt.

When they got to Glenfield, Kiriana Taiapa had a coffee and cigarette on the deck while her son began to panic, asking her a number of times what he should do with the weapons.

She told him to calm down because she didn't want to talk about it. After her son was arrested the next morning she feared police would gain a search warrant and find the weapons so she texted a friend and asked "if she could bring some shit over". The friend said no but she did anyway.

Police later found them at a Glenfield address.

While Taiapa was fretting over the weapons, Harlem Kirton and another young man, Clinton McGinty, were out walking on Takapuna Beach, about 6.30pm, where they came across Zaid Aqrawe and his friends.

They tried to talk with Mr Aqrawe's group but they walked away. McGinty walked aggressively up to them and when Mr Aqrawe intervened he was told, "do you want to start something".

Mr Aqrawe again tried to walk away but McGinty told him if he didn't speak to him in 30 seconds he would knock him out. A short time later he punched Mr Aqrawe in the face. Mr Aqrawe fell to the ground and McGinty and Kirton kicked him in the head several times before running off.

When the four men were arrested they had different versions of what went on. Taiapa denied any involvement, Wilson said he was there but downplayed his involvement and Harlem Kirton claimed only to have punched Mr Aqrawe in the head.

Piri Kirton told police he knew the aim of the night was to rob people, but he was only the driver.

Yesterday, to the relief of the victims who were spared giving evidence, the truth finally came out.