[1][2] The film was broadcast in the United Kingdom on the ITV network in 1986 With their father tied up with a long-term business contract, siblings Kate and Ben move in with their aunt.

Kate, Ben and Spider eventually decide to explore Castle House, a mysterious huge manor that has been abandoned for 15 years.

While Miss Markham proves to be very friendly, Mr. Wilberforce and his men strive to keep the children away from the grounds.

As the two boys disclose, Ah Leong's father was kidnapped by Wilberforce and his goons to help them in a break-in, since he is supposed to disable the security system, and is kept captive in Castle House's cellar.

Using Miss Markham's personal high-power speedboat, they catch up with the gangsters, overpower them and free Mr Leong.