The family of missing 15-year-old schoolgirl Samantha Osborn know this only too well.
Samantha disappeared five months ago after becoming involved with a man she met on the web.
It emerged he was not 16 as she'd claimed, but a 20-year-old unemployed man who had first messaged Samantha on Bebo just after she turned 15.
She lost interest in everything except chatting online and on her mobile. We still hoped it was a temporary phase, but when her school broke up for half-term on Friday, February 9, Samantha announced she was going on holiday to Wales - to stay with Paul. It was a ridiculous, wildly inappropriate suggestion. She'd never lied to me before, so I agreed she could have her Saturday outing.But the next day, Samantha left the house early, having packed a bag of clothes and her half-term homework.I found out she wasn't with her pals only when I rang her mobile that afternoon and asked her if she'd like a lift home. I tried to keep calm and told her to come straight home, but she refused, saying she planned to stay for the week.Her mother Gill, 40, a retail manager who lives with her husband Bob, 44, in Buckingham, tells their heartwrenching story.The pain of not knowing what has happened to my beloved daughter is like an open wound which has become more agonising every day since she disappeared.After one such trip in January, Samantha came home with a bag full of goodies. "A boy from school," she replied and I thought nothing of it. She then began getting calls on her mobile which went on for hours and often left her upset and tearful.