A group of four teenagers stabbed a 15-year-old boy more than 40 times in a "targeted, well-planned" attack in the back of taxi, a court heard.
Keelan Wilson suffered fatal knife wounds yards from his Wolverhampton home on May 29, 2018.
Wolverhampton Crown Court heard four 19-year-old men - Brian Sasa, Tyrique King, Zenay Pennant-Phillips and Nehemie Tampwo - planned to "execute" the teenager on Langley Road in the Merry Hill area of the city.
Prosecutors allege the defendants "set about him with weapons" and inflicted the 40-plus injuries while he sat next to a friend in a taxi.
Sasa and King, both of Wolverhampton, Tampwo of Bletchley, Milton Keynes, and Pennant-Phillips, whose address cannot be published for legal reasons, all deny a single charge of murder.
Opening the case against the men on Wednesday, prosecutor Michael Duck QC said: "It is a matter of real sadness that people of such ages have the willingness to take the life of another person.
"It is not just the fact they were prepared to take that life but the manner in which they chose to do it.
"This was not in any way a spontaneous act of violence.
"This was a well-planned, targeted group attack by a number of youths armed with knives, and that was with the plan to execute another young man."
Mr Duck continued: "The reason I say that is shortly before 11pm on May 29, 2018, in a residential street ... a group of youths ran towards their target Keelan Wilson as he sat in a taxi with a close associate.
"The group pulled open the rear door of that taxi and they set about him with weapons.
"He had inflicted upon him something over 40 knife wounds - at least three of these wounds could have been fatal."
The prosecutor told the jury the taxi driver suffered a "minor cut" and Mr Wilson's friend was unharmed in the attack.
Mr Duck said: "That act was committed by the group under the gaze of the public.
"If you, as a group, are prepared to behave in that way with people watching, what does that tell you about the group? They thought they were something akin to untouchable.
"That act inflicted these 40-plus wounds on that young man.
"This was not an attack by a single weapon.
"It means that, as awful as it is to consider... each member of that attacking group had been part of an agreement to end Keelan Wilson's life at 11pm that night by inflicting the most appalling violence on him."
The trial continues.