A student who vanished after a New Year's Eve Party sent a text message pleading for help.
Ms Geeson was last seen leaving a New Year's Eve party in Cambridge
Sally Geeson, 22, from Brookfields, Cambridge, was last seen on the morning of Saturday 1 January at the Hogshead pub in Regent Street.
In the message to her flatmate Miss Geeson wrote: "I've got into a car with someone please call me x".
Shortly afterwards she sent another message to a second friend which said: "Please help me x".
The text messages took several hours to arrive because the mobile phone system was jammed with users sending new year greetings.
Nothing has been heard from her since.
Sue Geeson appeals for her daughter to contact her
The recipient of the first message Janet O'Dea, 22, said: "I tried to phone her at 0915 GMT and it rang through to her answer machine. A few minutes later I tried again and the line just went dead.
"Obviously I was very worried when I got the text. I thought she may have stopped at a friend's house for the night because we have got a lot of student friends in the area.
She was expected at the Travelodge in Cambridge - where she worked. But when Ms O'Dea discovered she had not arrived at work she phoned family and friends to see if she was there.
At 2000 GMT she reported her missing to the police.
Speaking to BBC Look East Sally's mother Sue Geeson, from Southend, Essex, said: "If Sally's watching and there's a problem, it doesn't matter, just contact somebody... anyone."
Sally's identical twin sister Julie Geeson said: "Now it's the fourth day and we've heard nothing and there aren't any leads.
"I just feel sick, like your stomach is hollow and your mind plays tricks on you... you try to stay positive because it's the best thing to do for everyone. But you can't help thinking the worse."
On Tuesday officers visited the pub where she was last seen in the hope that someone would remember seeing her on New Year's Eve and would have information that could trace her.
A spokeswoman for Cambridgeshire Police said Miss Geeson, a student at Anglia Polytechnic University, was at the New Year's Eve party with a male friend.
It is thought she left the city centre pub with the friend to buy fish and chips in the early hours of New Year's day. Ms Geeson disappeared when her friend intervened in a group involved in a fight, she added.
When Miss Geeson's friend returned to the pub to search for her, he was told by a bouncer that she had re-entered the premises. This was the last time she was seen, police said.
Miss Geeson is described as white, 5ft 2in, of slim build with curly ginger hair.
At the time of her disappearance she was wearing glasses, a brown dress and brown high heeled shoes, and she was carrying a denim bag with a brownstrap.