The Attic Investigation Club decided to have a picnic behind the conservatory on the grass. They packed some sandwiches, cookies and lemonade in a basket and headed out. They found a nice spot under a big oak tree and spread out a blanket. They also brought a sac filled with photos they found in a dusty old chest, they found behind a curtain in the attic. They saw pictures of their grandmother when she was young, with her friends, family and pets. They also saw pictures of places they had never been to, like mountains, beaches and cities.

One photo caught their attention. It was very odd. It was a photo of an old red Ford Mustang convertible car. The car looked shiny and new, and it had a big bow on top of it. Their grandmother was sitting in the driver's seat, smiling and holding a sign that said, "Happy Birthday!"

They wondered why their grandmother had such a car and what happened to it. They decided to show her the photo and ask her about it. They put the photos back in the chest and locked it. Then they grabbed their basket and ran back to the house.

They found their grandmother in the living room, knitting a sweater. They showed her the photo and asked her where she got the car and where it was now.

Their grandmother smiled with joy when she saw the photo. She told them that the car was a gift from their grandfather on her 21st birthday. She said that she loved that car and had many adventures with it. She said that she drove it across the country with her best friend, went camping in the woods, watched movies at the drive-in theater, and even raced against other cars on the highway.

She said that she kept the car for many years, until it broke down and needed a lot of repairs. She said that she couldn't afford to fix it, so she stored it in the barn behind the house. She said that she hoped to restore it someday, but she never got around to it.

Holly and her sisters were amazed by their grandmother's story. They asked her if they could see the car in the barn. Their grandmother agreed and led them to the barn.

They opened the barn door and saw the car covered with dust and cobwebs. It looked nothing like the photo. It had flat tires, rusty parts, cracked windows and faded paint.

Holly and her sisters felt sorry for the car. They wanted to make their grandmother happy by fixing it up for her. They asked their grandmother if they could try to repair it. Their grandmother was surprised by their offer, but she agreed.

They decided to make it their summer project. They searched online for parts, tools and tutorials on how to restore an old car. They worked hard every day, cleaning, painting, replacing and fixing everything they could.

After several weeks of hard work, they finally finished their project. The car looked as good as new! It had shiny tires, smooth parts, clear windows and bright paint.

They surprised their grandmother with the car on her birthday. She was speechless when she saw it. She hugged them and thanked them for their wonderful gift.

She asked them if they wanted to go for a ride with her in her Mustang. Holly and her sisters agreed eagerly.

They got in the car and drove away with their grandmother. They felt happy and proud of what they had done.