the Authenticity of the Dungeon

It was summer of 1985 Emma, Edric and Elijah moved into a mansion which was 100 years old the day they moved in the house seemed so dusty and untidy they took 2 days to clean the mess completely and settle down but wierd things started happening soon they started hearing birds chirping even when it is night time and there was a sound of a running river when the literally lived in a area where there are no rivers or lakes this made them think they were hallucinating.
Emma was an author and was always working on fantasy novels which made her busy so she never cared about those sounds but Edric and Elijah always wondered if there was a portal leading to another realm where there were birds chirping even in nights and rivers flowing with the most peaceful noises as their holidays ended they started going to their university which meant they didn't have a lot of time to spend thinking about all the noises.
One day when Emma, Edric and Elijah were cleaning their basement they stumbled upon a wall which sounded like it was hollow Edric and Elijah tried to push it open but it seemed fixed so they dicided to break the wall open instead after they broke it there lied a great hallway which lead to two passageways they enter the one to the right and then the chirping noises and the noises of the flowing river grew stronger and stronger for each step they took them they found an other door which was locked they tried to break it open but it was too strong so they began searching for it and when they found it they realised it took over one week they found on the roof which was falling apart the movement they opened the door they were shocked to see a beautiful landscape with birds and butterflies and a waterfall which reflected  the blue light emitted by the moon they stayed there all night admiring the beauty of the mysterious place they named it as the dungeon Emma was thinking of ideas to add in her novel while Elijah was painting the beautiful waterfall Edric however was exploring the sight to find any expensive fossil or a rock .
The next morning they couldn't stop wondering about what was waiting in the other door the movement they went home they started looking for the other key but never found it as days passed on once when they were hanging out in the dungeon they saw something glowing in the pond nearby Edric dived in and brought it out they used it on the other door and inside stayed a lot of money which left them speechless they did some research on where the house was built and who were the previous owners they found out that before hundred years the mansion was actually owned by royal family which made secret entrences one which lead to a relaxing and a good hiding spot and one which has all their savings after knowing this they donated all the money to charity and continued their lives normally but one day and unexpected guest arrived at the mansion who seemed to be the heir of the royal family and wanted his mansion and money back they told him that the money was given to charity and that the house is now legally owned by them but he didn't some asking for it and even threatened them and  he started attacking by throwing the things at them which hurt Elijah on his head that's when Emma rushed to call the cops and they took him away they later took Elijah to the hospital and he was fine but had a syndrome because of which his accent had changed it was pretty hard for Emma and Elijah to understand him but they soon got to understand him better and everything was going good Emma soon published her novel and became an author she even earned quite a lot of money which helped them live Edric became an archeologist and Elijah became an artist they all changed but one thing that didn't change is that they always hang out in the dungeon