The pair were gagged and bound before 57-year-old Gordon was bundled from the property and thrown down a steep embankment into the River Almond.

The brutal gang then made off with the terrified pair’s car.

Annabelle’s son Douglas Stewart (30) said his 58-year-old mother feared for Gordon’s life during the raid.

“Gordon was dragged out and my mum was convinced she wasn’t go to see him again,” he said.

“The gang even grabbed her pet cat and threatened to slice its throat.”

Douglas said the gang appeared to be searching for cash.

“A CID officer told me this was one of the most horrific cases she has ever worked on,” he said. “The people responsible are pure scum.”

The trio of masked raiders all spoke with local accents and detectives have launched an urgent appeal for information.

It is understood Gordon was threatened with an array of weapons, including knives, during the hour-long ordeal.

The couple, who were alone in the house, were left tied up but managed to escape and raise the alarm.

They were extremely shocked but did not suffer any serious injuries.

So far there has been no trace of the three assailants.

A spokeswoman for Tayside Police said, “Around 8.45pm on Tuesday three masked men entered the house situated within the Dalcrue Auto Salvage compound near Pitcairngreen and tied the couple up.

“A 57-year-old man was then assaulted and threatened with a knife and other weapons. At one point during the incident he was taken from the house and thrown down a steep banking into the nearby River Almond.

“The couple were left tied up while the men made their escape. Both victims managed to free themselves and summon help.”

Police said the trio wore dark clothing and balaclavas. Two of the men were of slim build and the third was larger.

Anyone with information that could help police or who was in the Dalcrue area on Tuesday evening is asked to contact police on 0300 111 2222 or speak to any officer.

Information can also be passed on anonymously to Crimestoppers on 0800 555 111.