Ellery Queen Mystery Magazine. Vol. 133, Nos. 3 & 4. Whole Nos. 811 & 812, March/April 2009

“That’s what I said.” Louise D’Acre trapped her phone between her ear and her shoulder, using both hands to read through her notes. “In fresh water, or they had had a heart attack.”

“I’m sorry, Dr. D’Acre, I don’t follow.” Hennessey moved the phone from one ear to the other as he heard Dr. D’Acre smile down the phone.

“I’m the one who should be sorry, I’m not making a great deal of sense, am I? I was puzzled, because the cause of death was apparent upon investigation. Both corpses show evidence of vagal inhibition of the heart, which brought on a fatal heart attack. Death from such causes is often associated with shock, especially in the frail elderly, but as I pointed out, both died at exactly the same time. So what caused two young and healthy people to die of shock at the same time? That had me foxed. And if their deaths hadn’t been linked, if their bodies had been found miles apart, for example, and at different times, I probably wouldn’t have looked for a link, and would have put death down to heart failure, caused by vagal inhibition. But they were clearly linked, so I had a closer look and found the answer in the marrow of the long bones.”

Thus far Hennessey had written “heart attack” on his notepad but continued to listen patiently.

“I found diatoms in the long bones.”

“Diatoms?”

“Wee beasties, as a Scotsman might say. Microorganisms that live in the water. They get into the marrow of the long bones of a drowning victim. They differ from saltwater to freshwater, these are freshwater diatoms. And the victims’ blood has expanded in the veins, caused by the freshwater joining the bloodstream, saltwater doesn’t do that, so they drowned in freshwater. And I would guess a struggle for life induced vagal inhibition, which brought on a heart attack. No signs of violence, though, except for small areas of light bruising round the ankles of both victims. Both of her ankles, and one of his ankles.”

“The ankles?”

“They were held facedown in a large body of water by someone holding their ankles. The water was clean, not polluted, and heavily chlorinated. A swimming pool, for example.”

“Funny you should say that.”

“Why, is it significant?”

“Very.”

“Well, diatoms differ from one body of water to another. If you could obtain a sample of water from the pool in question, I could tell you if our two friends here drowned in that pool.”

“What are you looking for, boss?” Yellich drove out to the Oast House, Allingham.

“A swimming pool.” Hennessey sat in the front passenger seat and went on to tell Yellich about Marina Westwood’s hair smelling of chlorine. He also told him about diatoms and vagal inhibition.

The Westwood house in Allingham was a sprawling bungalow set in expansive grounds. A large car and a small car stood in front of the building, saying clearly “his and hers.”

Marina Westwood opened the door almost immediately upon Hennessey ringing the doorbell. She looked surprised to see Hennessey. Hennessey remarked upon the fact.

“No... no...” she stammered. She was dressed fetchingly in faded jeans, leather belt, and a blue T-shirt. “Well, I suppose I am... I thought that yesterday was it, just identify him. What do you want?”

“Your husband died in suspicious circumstances. We’d like to look at your house.”

“Do you have a warrant? On television...”

“Do we need one?” asked Hennessey.

“Are you hiding something?” asked Yellich.

“No,” she shrugged offhandedly, and stepped aside, allowing the police officers to step over the threshold.

It was a large, spacious house inside, very light, very airy, with interior walls of unfaced brick.

“Where is the swimming pool?” Hennessey asked suddenly.

“Down there.” Then Marina Westwood’s face paled.

Hennessey saw her pale and he knew a chord had been struck, and he knew this inquiry was drawing to an early close. It was so often the case, he thought: Before you look at the outlaws, look at the in-laws. “If you’d lead the way?”

Marina Westwood led them down a narrow corridor to the indoor swimming pool. Thirty feet long, twenty wide, brick walls on three sides, the fourth wall was given over to tall windows which looked out over the rear lawn. Hennessey took a test tube from his pocket and knelt and dipped it into the pool and sealed the contents. “You haven’t changed the water in this pool since they drowned in it, have you?”

“No.”

A pause, a look of horror flashed across her face. Marina Westwood screamed and ran from the poolside into the body of the house. Yellich lunged at her as she ran past him, missed, and started to run after her.

“Don’t.” Hennessey placed the test tube in his jacket pocket. “She’s not running from us, she’s running from herself, either that or she’s engaging with life for the first time. Either way, we’ll find her sobbing on the sofa somewhere.”

In the event, they found her on the rear patio looking out over the garden, sobbing quietly. Hennessey stood beside her.

“You know,” she said, “this was all going to be mine.”

“Was.”

“Can’t profit from a crime, can you?”

“No.”