Police are looking to speak with two people who came to the aid of a young woman after she was raped in Helensburgh.
Officers are investigating the incident which took place between 10.30pm and 11.30pm on Saturday near East King Street in the city centre.
A 22-year-old woman was subjected to a serious sexual assault before being approached by a man and a woman a short time later.
Police are keen to speak to the Good Samaritans as their probe into the attack continues.
Detective Inspector Allison Campbell said: "I am appealing for a man and woman who spoke to the victim who was distressed to come forward.
"They spoke with her sometime between 10.30pm and 11.30pm while she was on her way to Helensburgh train station. It is believed the man and woman had made a recent purchase at a local takeaway restaurant.
"Enquiries are underway and officers are reviewing CCTV and there will be extra patrols in the area.
"Anyone who was in the area and has information should contact Police Scotland on 101 quoting 342 of Sunday, 16 August."
Meanwhile, police are also investigating the rape of 16-year-old girl who was attacked in Glasgow Green on Saturday night.
