He was due to celebrate his 25th birthday on New Year's Eve. His mother Mary Byrne said somebody must know what happened to her son. "I think there is trouble and while I always have to have hope, I also fear the worst," she said.
"I think that if he had harmed himself in any way he would have been found by now. This is a living hell for us. If anybody knows anything they need to tell somebody."
The last time the catering worker was seen was at around 3am on Christmas Day at the cottage he rents with housemates on Sandy Lane in the seaside town of Rush.
He sent a text to his girlfriend wishing her a happy Christmas at 10.30am -- the last known contact he had with anyone.
Since then, his mother and siblings Stephen (29), from nearby Lusk, and Suzanne (27), from Clontarf, have been frantically searching for him.
"The last time I was talking to Paul I felt that maybe there was something on his mind, and some of his friends said he was feeling down about the death of his father," Mary added.
Paul is 5ft 5in tall, slim with blue eyes, and light brown hair.