A woman threw messages in bottles from a multi-storey window after her boyfriend abducted and attacked her, a court has heard.
John Lawson assaulted Klaudia Budzinska and locked her in his flat in Dundee after she tried to leave.
Miss Budzinska abandoned an attempt to escape down a knotted bed sheet from the fifth floor flat while Lawson slept.
Lawson, 35, will be sentenced in September after admitting the offences.
Dundee Sheriff Court was told that he had pinned Miss Budzinska down and choked her, before falling asleep.
Miss Budzinska put the first note in a bottle and threw it at a passerby who did not see it.
A second note was picked up by a man who looked up to see Miss Budzinska standing on a balcony making a "be quiet" gesture, running her finger across her throat and making a praying motion.
'He almost killed me'
The note read: "Call police, he almost killed me. Don't buzz or knock. Kick the door in. Pls help."
Depute fiscal Vicki Bell told Dundee Sheriff Court: "Police attended at around 08:00.
"Fresh injuries were observed on her when they gained entry including multiple bruises on her face and neck and a cut and swelling on her lip.
"In relation to the compression of her neck, she said he was squeezing it so hard with both hands that she couldn't breathe or say anything.
"When she was locked in she couldn't find a key to get out or find her phone.
"She was certainly a desperate woman at the time."
Lawson, a prisoner at HMP Perth, pleaded guilty to charges of abduction and behaving in a threatening and abusive manner.
Sheriff Alastair Brown deferred sentence until 13 September and remanded Lawson in custody.
He said: "Compressing the neck and restricting her breathing is exceptionally serious."