A nine-year-old boy was threatened at knifepoint by a man who demanded he go into woods to play 'truth or dare'.
The attacker, who was carrying a flick knife, was only frightened off when the boy's sister came across them.
The boy was playing near to his home in Bracknell, Berkshire, when he was grabbed and dragged to the woods.
Police have laid on extra patrols around the Hanworth Road and Birch Hill area to reassure local parents after the incident at 1140 BST on Sunday.
Detective Sergeant Steve Witts said: "Fortunately the young boy was not injured but nevertheless was left shaken and upset by the very nature of this worrying incident.
"I would like to reassure both parents and children that a detailed investigation is being carried out following yesterday's incident and that extra patrols are being carried out in the area."
The attacker is described as white, thin, with short dark hair and a spotty nose and was wearing a black t-shirt, dark blue jeans and black trainers.