Conceal

There was a big hole behind the frame, which led to the back of the house.

"The one who created this opening should've had a reason." Said Della with excitement.

Della paced inside the hole with so much eagerness.

Robin tried to stop her, but Della neglected his words.

They got to the other side, The sun was shining bright, the sky was vast and endless it had calm clouds.

Della smiled serenely.

Robin was still admiring the sky. They got back to their sense and went to explore the place.

"We have to bring Mike and Lexi here the next time. I am sure they'd love this scenery!" Exclaimed Della.

They heard a strange sound while walking on the land. Robin aggressively moved the rocks.

They saw another opening there. Robin went inside first, while Della followed him.

When they reached the end of the stairs, they saw a door.

And Robin opened it. It was a basement which looked like a regular workplace for a doctor.

"Robin, I am sure we can get some clues here. And I'm glad that you came with me." Said Della with excitement.

"It is my duty, Isn't it?" Asked Robin.

"It sure is!" Answered Della.

They started to explore the basement.

It was a small room with a desk, a chair and several shelves. The shelves contained bottles of medicine and books about medicine.

The drawer looked normal until...

"Hey, Robin, look at this!" Said Della.

But, Robin was busy searching the shelves. The drawer had a false bottom.

A bottle of opened white vinegar was kept inside to avoid bugs from entering.

It contained some books.

Della proceeded to search if there was any clue inside the books. In one of the books, Della found a picture.

"Robin, I think I got a very important clue." Said Della with a trembling voice.

They both examined the picture. They saw nothing but a picture of an old mask. Robin realised that something was written on the backside of the picture.

Before Della looked at it, Robin suggested, "Della, we found a clue. We'll head back home. It is getting late." Della assented and went back with him.

Lexi was awake already, and she welcomed them.

"We went to t---" Robin was interrupted by Della.

"We went for a walk." Della finished the sentence.

"Why're you acting strange, Della?" Asked Lexi.

"It's because we were walking for a long time, don't bother about this Lexi." Said Della with a grinned smile.

"Would y'all like a cup of coffee?" Asked Della's father.

"Of course, Mr Arthur." Said Lexi.

"I will have my cup of coffee later, Dad." Said Della.

Della went to her room, and Robin followed her.

"What's wrong with you, Della? Why did you lie to Lexi?" Asked Robin.

" I feel like this should be a secret until we find out what it is." Said Della.

"But Lexi is one of us." Protested Robin.

"We are not sure if this really is a clue." Said Della.

"Fine, where is the picture now?" Asked Robin.

Della took the picture out of her pocket.

She turned the picture to read what was written there. The words were written in Danish.

Suddenly, They heard someone knocking their house's door.

Della kept the photo safe inside her bag and went out to see who was knocking the door.