The rain had been falling since shortly after dusk when Detective Sergeant Edmund Cryer was called to a narrow house on Blackburn Road.

The occupant, fifty-eight-year-old widower Joseph Waddington, had been found dead in his upstairs bedroom.

At first there appeared to be nothing unusual about the death. Waddington had gone to bed shortly after ten. His neighbour, Mrs Ellen Ward, had heard nothing during the night.

The bedroom door had been locked from the inside. The window was secured. There was no second entrance.

And yet Mrs Ward insisted that, at precisely two seventeen in the morning, she had heard a man speaking inside the room.

Not shouting. Not arguing.

Simply speaking.

She could not make out the words. Only that there had been two voices.

Cryer examined the room.

Waddington lay beside his bed, fully dressed. The doctor believed he had died from heart failure.

Cryer was not satisfied.

On the table stood a paraffin lamp. Its flame had gone out, but beneath it he found a small patch of melted wax.

There was no candle in the room.

Then he noticed something beneath the bed.

A boot.

Not Waddington's.

It was a man's black leather boot, heavily worn and still damp from the rain. The sole carried three narrow horizontal cuts.

Before leaving, Cryer asked Mrs Ward one question.

"When you heard the second voice, did it sound as though the man was speaking to Mr Waddington?"

She hesitated.

"No, Sergeant."

"What then?"

"It sounded as though he was answering him."

Cryer returned to the bedroom.

On the inside of the door, almost level with the lock, were three shallow scratches in the wood.

He recorded them carefully.

Then he opened the bedroom window.

Beneath the rainwater on the sill was a single muddy fingertip impression.

On the inside.

The boot was locked in the evidence cupboard at the station.

By morning it had disappeared.

No officer admitted removing it.

Cryer never discovered who had entered Joseph Waddington's bedroom that night.

The official cause of death remained heart failure.

In his private journal he recorded only six words:

"Waddington did not die alone."