Today marks the 18th anniversary of the disappearance of Trevor Deely.
The 22-year-old went missing while returning home from his office Christmas party in Dublin in 2000.
Despite a cold-case review, a major search earlier this summer and a 1 hundred thousand euro reward for information, his disappearance remains a mystery.
Trevor's father, Michael Deely, says someone out there knows what happened to him:
Mr Deely said: "He went in after his party and after he had been on Leeson Street with a couple of his pals as well, and got a very big umbrella. Now, where has that umbrella gone?
"The night was so bad, you could well imagine that umbrella being blown away. People coming home from other office parties that night may remember. Someone somewhere has information, we feel, and we need to get that information."