Inside the TARDIS

The TARDIS arrives on Earth, at Cranleigh Halt railway station. The Doctor, Adric, Nyssa and Tegan Jovanka discover that the date is the 11th June 1925. They are then taken aback to be met by the chauffeur of a Lord Cranleigh and driven to a cricket match where The Doctor ends up winning the match for the home side. Lord Cranleigh and his family, assuming that The Doctor has come from Guy’s Hospital, invites them all to a masked fancy dress ball.

Unbeknown to The Doctor and his travelling companions Nyssa is the spitting image of Ann Talbot, Charles’s fiancé. When they arrive at Cranleigh Hall costumes are chosen for them including identical butterfly costumes for Nyssa and Ann while The Doctor chooses a harlequin outfit. But while The Doctor is taking a bath, a stranger enters his room via a secret passage. The Doctor fails to see the stranger but, on returning to his room, he notices the open door to the passage and goes through it. The stranger meanwhile makes off with harlequin costume that was intended for The Doctor.

At the ball, Nyssa and Ann are having great fun confusing everyone as to their true identities. Un-noticed by anyone Lady Cranleigh is taken to one side by a South American Indian named Dittar Latoni, who explains that Digby, one of the servants, has gone missing. They go to investigate, leaving Tegan dancing the Charleston and Adric eating. A character in a harlequin costume then appears and entices Ann to dance with him. But when they are alone in the hallway the person in the harlequin costume approaches her threateningly. Rescue comes in the form of a footman who tries to intervene. The footman though is killed.

The Cricket Match

The Doctor, meanwhile, has found a dead body in a cupboard. When Lady Cranleigh and Latoni arrive The Doctor shows the body to them and it is identified to be Digby. Meanwhile the harlequin costume is returned to The Doctor’s room by the stranger, who then goes to another room and puts the unconscious Ann to bed there.

Ann soon recovers and runs out to Lady Cranleigh. At that moment The Doctor appears on the stairs wearing the harlequin costume and Ann accuses him of attacking her. The Doctor tries to explain but Lady Cranleigh will not corroborate any of his stories of secret passages and dead bodies. Sir Robert Muir, the local police chief, then arrests The Doctor on suspicion of having killed the footman, James. To make matters worse for The Doctor, and his travelling companions, Charles then receives a phone call from a man named ‘Smutty’ who tells him that the replacement cricketer, for whom The Doctor has been mistaken, actually missed his train.

Lord Cranleigh

On the way to the police station, The Doctor gains Sir Robert’s permission to stop off at the railway station but to his dismay, the TARDIS has gone. Luckily is has just been moved to the police station. There, The Doctor takes Sir Robert, Sergeant Markham and Constable Cummings inside to prove that they are innocent.

Back at Cranleigh Hall, Lady Cranleigh admits to Charles that she and Latoni have been secretly looking after his brother, George Cranleigh, who was presumed dead after apparently failing to return from an expedition he made up the Orinoco River two years earlier in search of the black orchid. He has been hideously scarred - both physically and mentally - by the natives to whom the flower is sacred.

In a secret room Latoni is knocked unconscious by George Cranleigh but, by hiding the door key between two floorboards, prevents him from escaping from the room in which he is being held. Unable to find the key, George Cranleigh starts a fire to burn through the door.

Ann Talbot

The Doctor transports everyone back to Cranleigh Hall in the TARDIS. There they discover the fire. Suddenly without warning Nyssa is snatched by George Cranleigh, mistaking her for Ann, as he escapes from the burning room, and is dragged upstairs and onto the roof. But The Doctor is unable to follow them because the fire has spread.

Sir Robert demands to know who the deformed figure is, and Lady Cranleigh explains that the Kajabi Indians disfigured George Cranleigh and cut out his tongue. Latoni was the chief of another tribe who rescued him and brought him home. Thinking that George Cranleigh has snatched Ann she also insists that he will not harm the girl. But The Doctor points out that it was not Ann he took but Nyssa.

While trying to find another way up onto the roof everyone leaves the house it is then that Lady Cranleigh confesses to Sir Robert that it was George Cranleigh who killed Digby. Up on the roof The Doctor implores George Cranleigh to release Nyssa, telling him to look down and see Ann. On releasing Nyssa, Charles approaches his brother to thank him, but George Cranleigh backs away and falls from the roof to his death.

Later, on returning from George Cranleigh’s funeral, The Doctor and his travelling companions, as they are about to leave in the TARDIS, discover that Tegan has been given a large box containing their fancy dress costumes, which they have been allowed to keep. Lady Cranleigh also gives The Doctor a further gift: a leather-bound book The Doctor thanks her and opens the first page. Opposite a photograph of the author is the legend: ‘Black Orchid by George Cranleigh’.