When Scott, Jack and Emily stumble upon some bones in the quarry above Castle Key, they're convinced they've discovered the gruesome remains of a murder victim! But the bones turn out to be much, much older than that - could they be dinosaur bones? Or are they the last earthly remains of a real dragon? Rival scientists fight to prove each other wrong, while the friends are determined to uncover the truth - with a little help from Drift the dog, of course!

Something strange is afoot on the moors above Castle Key - sinister noises, lights in the sky and mysterious figures moving in the dark. Are aliens invading, as Jack suspects? Could it be smugglers, as Emily thinks? Or is there another explanation? Scott, Jack, Emily and Drift the dog are on the case!

When Scott, Jack and Emily rescue a drowning man from the waves they are keen to hear his story, but their new friend can't remember his own name, let alone how he came to be stranded at sea! Who is the mystery man? Why did he come to Castle Key? And was his drowning an accident - or attempted murder? The friends are on the case - with enthusiastic assistance from Drift the dog - determined to find the truth and solve the mystery of the drowning man.

When Boomerang the cat disappears into a tiny gap behind the fireplace at Stone Cottage, Scott, Jack and Emily are amazed to discover a secret room that Aunt Kate never knew existed! But what was the room created for? Inside is very little other than an enormous old chest which Jack is convinced must be full of treasure, but what secrets will be revealed when the friends finally manage to open the box?

A research team arrives in Castle Key to explore the wreck of an old smugglers' ship that sank in Pirate Cove. When Scott and Emily dive down to the wreck, Scott glimpses a long lost artefact said to hold the key to a hoard of smuggled treasure. But when the team leader goes back to recover the artefact, it has mysteriously vanished! Was Scott mistaken or is somebody else after the smugglers' loot? Follow Scott, Jack, Emily and Drift on a very mysterious treasure hunt.

There's a new resident in Castle Key - and somebody is watching him! Scott, Jack, Emily and Drift soon suspect that the new resident is an enemy spy. It explains the bullet-proof glass in the windows of his house. And the MI5 agent who is clearly keeping tabs on him! But what is an enemy spy doing in Castle Key? Can the friends reveal his true identity? And uncover his top secret mission? Join Scott, Jack, Emily and Drift as they investigate a man so mysterious he's almost invisible!