Although the gun mechanism used in the brick was similar to the gun mechanism used in the clock ( Dolly Bondra case) but the whole story was definitely different and nicely executed.
So, there is one Mharajah without a kingdom who is a five time widower and is looking for his luck sixth time. A woman younger to his only son is his next wife. The young Yuvraj who is blind is visibly annoyed to have just another step mother in his life. There is one woman in the house who is working as a help here and her 25 year old son. Along with them is a servant who is a dwarf. Along with everything else there is a story of a curse that has killed all the Ranis of this palace.
In the next scene Mahrajah and the Yuvraj have a a heated conversation . A few minutes later former has been killed and the latter has been accused of it. He has been found with the gun which was used to murder his father. So, its an open and shut case .
From preliminary investigation it is proved that the murderer has shot the bullet but not straight. Its but from waist length the gun was shot. This makes a good point for the Yuvraj. KD explains that a blind man cannot have such accurate shot. The prosecution however proves that the YUvraj is a talented shooter despite of his shortcomings. KD however proves that the gun which was used was a old one which gets so heated after a third shot that it would burn the hands of the murderer if six shots were actually made that day.
In the next move, KD after questioning the servant finds out about the secret opening in the room the Maharajah had died. However, it is proved that only the would be wife of the Mahrajah knew about it. It is then proved that she is already married to the Mahrajah on papers and also that the Palace now belonged to her anyways. After questioning the servant it is further learnt that there was no curse at all but the Mahrajah loved to remain secretive about his life.
Finally in the court KD proves that only first two Ranis of the Mahrajh died naturally. Others died under suspicious circumstances and they were brushed off as the effect of the curse on the Palace. He also proves that the woman who works in the Palace who claims to be a widower was never married but has a son. Then it is proved that she was a mistress of the Mahrajah and lived in the palace as she hoped that man will ever marry her. Her son out of frustration admits he had killed the Mahrajah. He was frustated with the man who was his biological father. He killed the Ranis one after other with a hope that he will marry his mother but he never did. So, finally he killed him.
KD explains the whole process. Maharajah had a fire place. The murderer had placed a metallic brick there which worked like a gun when heated. It was later replaced with a new one. That's how KD noticed it because all the bricks were black due to fire except this one.
Thus, another case was solved.