CCTV images have been released of a 16-year-old from Aberdeen who has not been seen since Saturday.
Liam Smith is understood to have caught the 202 bus to the Deeside area.
He is described as white, 6ft 4in tall, of slim build, with short, brown hair. When last seen, he was wearing a dark top, blue jeans and trainers. He is also thought to be carrying a camouflage backpack.
Police Scotland appealed for the teenager to get in touch.
Insp Jackie Knight said: "Liam was reported missing to police on Sunday morning but he was last seen during the afternoon of Saturday. Given the passage of time his family is naturally becoming increasingly concerned for his welfare.
"We are asking that if anyone saw him on board the 202 bus on Saturday that they contact us. We just want to make sure he is safe and well as soon as possible.
"Inquiries are ongoing with the bus company to establish where and when Liam got off the bus but we would urge anyone who saw him on the bus or has seen him in the Deeside area to contact police.
"I would also appeal directly to Liam that if you are reading this you contact police to let us know you are OK."