Sir John and Marie walked into the kitchen. Lord Arlington was standing there, looking more composed than they had seen him.

“Sir John,” he said, “I’m afraid I don’t have a wife.”

“Indeed,” said Sir John. “As we knew from the start. There was an imposter in your house.”

“Another phantasm!” said Lord Arlington. “Of course, they were wily creatures, but you stopped them Sir John. How?”

Sir John walked with Marie to where the broken pipe was. 

“It was here, wasn’t it, where you argued,” said Sir John.

Lord Arlington kept a little distance and nodded.

“This was where the expert you had hired explained the situation. The inbound gas pipe for the ovens was being polluted with ethylene, which occurs naturally on your lands, but deep underground. The gas pipes were porous, and were allowing the ethylene to seep in,” said Sir John.

“Yes! Yes, that’s right,” said Lord Arlington. “It’s clearer now. The gas was affecting the staff, making them hallucinate.”

“The scientist wished to exploit this gas, but you refused… Am I right?” said Sir John.

“Indeed, there was an argument. He said there was great profit to be made, and I said all I wanted was for my house to be safe to live and work in. I didn’t want the money,” said Lord Arlington.

“Can you remember what happened then,” said Sir John, gently, “at the end of the argument?”

Lord Arlington looked confused for a moment, then looked sad.

“I’m dead, aren’t I?” he said.

“I’m sorry Lord Arlington, but it’s true. That was our third mystery. This scientist ripped out a piece of the piping, fully releasing the ethylene into the house. He hit you over the head and you died. It was in the newspapers “Lord Arlington murdered. Police accuse Professor Plum with the lead piping in the kitchen.”

A tear ran down Lord Arlington’s face.

“Then, why am I here?” he said quietly.

“The sudden release of gas was catastrophic,” said Sir John. “The household was driven to wild hallucinations and abandoned the house. The only heir was a long distant cousin, who was afraid of the stories. He put the house up for sale. I… imagine you felt the need to stay, so it wouldn’t fall into the wrong hands.”

“Mon cher,” said Marie. “I have to ask, how did this gas affect him if he was a ghost?”

“It didn’t,” said Sir John. “He was reacting to the people around him. As a phantasm himself, he thought their hallucinatory reality was true. But now, Lord Arlington, the gas is stopped and the hallucinations will go. People can return to the house.”

Lord Arlington looked at the couple.

“So,” he said, “now those greedy developers won’t get the house. Because of you.”

Like his fictitious wife, he started to fade.

“Thank you,” he said and disappeared.

Marie smiled at her husband.

“That was well done,” she said.

“Three mysteries in one,” said Sir John. “A bargain.”