Another 'was this an episode...' question

I remember a one-off drama that I think might be an episode of TOTU, or if not can someone please let me know what it is! This is written from distant memory, so the details might be imagined, but this is the gist:

It starts when a teenage boy is dropped off on a remote moor by his dad, he is going for his orienteering scout badge or something like that. He is wearing a bright orange jacket and has camping equipment, a map and compass etc. He arranges with his dad to rendez-vous at a specific spot so many miles away after two days' trekking.

The first night everything starts to go wrong, the weather turns bad, his equipment begins to fail and more worryingly he becomes aware of somebody unseen in the dark at his camp. This person follows him, sometimes getting ahead of him, sabotages his tent when the boy is away collecting firewood, stuff like that. Over the course of the trek the boy becomes increasingly scared and desparate as he is harassed by this other person, who you never see but perhaps catch the odd glimpse of, when he is committing some mischief or other.

Finally at the end of the episode the boy is beginning to suffer from exposure, his jacket having been stolen, and he stumbles shivering through the driving rain to the meeting point where his dad is due to pick him up - it seems he will be OK. But as he walks towards the road in the distance we see the mysterious figure is waiting by the road, and he is wearing the boy's orange jacket. And as his dad's car pulls up the mysterious figure walks to the car, seems to greet his dad through the window, gets in and they drive off leaving the boy stood in the rain out on the moors as night is drawing in. I.e. the figure is some sort of evil doppelganger that replaces the boy who is unknowingly (by his family) left to die alone on the moor.

Creepy, huh? But is it an episode of TOTU, or what?





"Man's mind is so formed that it is far more susceptible to falsehood than to truth"