In September 2002, house hunters Anthony and Linda O'Malley from North Wales arrived in Benidorm of Spain's Costa Blanca to bid for a house at auction that they had earmarked for their retirement. Within a week of their arrival, the couple vanished. Alerted by the withdrawal of large sums of cash from the couple's UK bank accounts the Welsh police launched their own missing persons inquiry. Daughter Nicola Welch, frantic with worry but with no idea of what really happened, made an appeal on Crimewatch for her parents to get in touch.Six months after the couple's disappearance, following emailed ransom demands from a mysterious figure codenamed Phoenix, Spanish police recovered their bodies from the cellar floor in a villa in Alcoy. The full horrifying story was pieced together in a painstaking investigation. The O'Malleys had been tricked into viewing the property, held captive for five days and forced to hand over the money they'd saved for their deposit. When they were no longer of use, they were disposed of in the cellar of the very house they'd hoped would be their dream home.Investigative journalist Danny Collins helped North Wales officers track down the killers in a tense and dangerous search - this is what he uncovered.