Lady Janet Douglas was born about 1502. She was the daughter of George Douglas, master of Angus and Elizabeth Drummond. She was the granddaughter of Angus Douglas.

Her brother was Archibald Douglas, 6th earl of Angus. Archibald was married to Margaret Tudor, the mother of King James V. James V became king at a very young age and after Margaret was removed as guardian of James and fled to England, Archibald took control of the young king and had him imprisoned in 1526. James V was released from prison in 1528 after Margaret Tudor divorced Archibald. Archibald fled to England and James V unleashed his wrath on the Douglas family.

Janet Douglas married John Lyon, 6th Lord of Glamis. They resided in Glamis Castle, which is near Dundee, Scotland. Janet gave birth to a son, John. When John Lyon died in 1528, James V tried to blame Janet for his murder since he had died alone after eating. A trial was held but Lady Douglas was acquitted due to lack of evidence. She then married Archibald Campbell and by all accounts it was a happy marriage.

In 1537, Janet was accused of trying to poison King James V by way of witchcraft. In order to gather evidence against her, her family and servants were tortured to give false evidence. On July 17, 1537, Lady Janet Douglas was burned at the stake at Edinburgh Castle. Her young son, who was now 16, was forced to watch. He had been implicated in the so-called murder plot and had been sentenced to death, but it was commuted to a life sentence due to his age. Her husband Archibald was also imprisoned, he died in an escape attempt. The Douglas family lands and properties were confiscated. After the death of James V in 1542, John Douglas was released from prison and the family properties were returned to him, including Glamis Castle.

The burning of Janet Douglas was a true blight on Scottish history. But, she has not been forgotten. Some believe that she is the grey lady who haunts Glamis Castle. People have reported hearing the sound of a scaffold being built. The grey lady has been seen praying in the family chapel and wandering the clock tower.