When three young detectives stumble upon a secret in a terror-filled castle, they must use their skills to unravel the mystery while facing disguises, steampunk elements, and haunted-house scares.

When the Three Investigators go on vacation in South Africa, they find themselves embarking on a thrilling treasure hunt on Skeleton Island. As they unravel the legend of a pirate's treasure, they must outsmart an art thief and solve various mysteries along the way. With the beautiful backdrop of Cape Town, South Africa, the young detectives face danger and excitement in their quest for hidden treasure.