In this guide, we will let you know a secret in the game.
It is located next to Callahan Manor. There is a symbol at these rocks as shown in the image below.
Also there is something underneath the rocks. Make your avatar taller and aim with a pistol in the first person.
You will see an elevator thing. There is a room down there. Try to blow it up with Detonator.
This may not work. Try TNT, place it on a circle where you see the symbol.
And it is Boom Boom time, let’s detonate it.
Well that damaged you but did nothing to the rock and shooting at the symbol does nothing too.
There is another symbol here in the graveyard but nothing is inside it.
There is also a secret room in the Manor. Enter into the room and click the green book.
And go inside the room in the basement behind this bookshelf. Don’t know if this is related to the elevator.