A woman was subjected to a "horrific" sexual assault after accepting a lift home from two men driving transit vans in Glasgow city centre.
The 37-year-old was waiting for a bus at Oswald Street at about 0030 BST on Tuesday 8 June when she got into one of the vehicles.
The driver headed to a car park at Scotland Street where the woman was sexually assaulted by both men.
Det Sgt Mick McCarron of Govan CID said the woman was "extremely traumatised".
He said that before the attack, both vans had been spotted travelling together at various locations in the city.
He added: "The victim was subjected to a horrific ordeal by these two men.
"She was subjected to a very serious assault which has left her very traumatised.
"It is absolutely vital we trace the two men involved."
It is thought the men were named Clark and Josh or Joshua.
After the attack the men drove off, leaving the woman in Scotland Street, where she walked to nearby premises to get help.
The man whose van the woman got into was described as white, aged 30-40, 6ft tall, of stocky build.
He was clean shaven and had short light brown hair in a spiky style.
He was wearing blue jeans and a dark T-shirt.
The second van driver was also described as white, aged 28-32, 5ft 9in tall, of slim build.
He had short blond hair, in a spiky style, and was wearing three-quarter length white shorts, a white T-shirt and white trainers.
The force has appealed for anyone with information about the attack to come forward.