The letter was from a wealthy businessman, Mr. Kumar, who owned a sprawling mansion on the outskirts of the city. He requested Chacha's presence at his mansion, stating that it was haunted by a ghost.

Chacha smiled, puffing on his cigar. "It's all in a day's work, Sabu. Now, let's head back to the office. We have more cases to solve."

As they explored the mansion, they stumbled upon a hidden room. Inside, they found a series of cryptic messages etched into the walls.

Chacha smiled reassuringly. "Don't worry, Mr. Kumar. We'll get to the bottom of this."

Chacha's eyes lit up. "Ah-ha! This is our first clue, Sabu."

The next day, Chacha and Sabu arrived at the mansion, which was a grand structure with towering spires and large windows. Mr. Kumar greeted them nervously.

The ghostly figure began to communicate with Chacha, revealing a shocking truth. The family member had been murdered by none other than Mr. Kumar's own business partner.