A 16-year old had his iPad and headphones stolen after being attacked by two men in an underpass in Leadenhall.
The teen was walking through the underpass from Milton Keynes College on Friday at around 1.30pm when a man put his arm around his throat and pulled him down.
The second man then took the items before they met with a third man and walked towards Oldbrook.
The trio are all black and in their early twenties. The first man, who grabbed the boy, is slim with short blond hair and big ears. He was wearing a grey hooded top with a red and black logo on the back and grey tracksuit bottoms.
The man who took the iPad is of a medium build, 6ft tall wearing black, loose clothing and a black hat.
The third man is large with a stubble beard, wearing a black hooded top and trousers with a black beanie hat with a peak. He was carrying a big, black sports bag.
Any witnesses can call police on 101 or Crimestoppers, anonymously, on 0800 555 111.