The koi in our pond had spawned a dozen baby fish, ample rain had juiced up the plants in the garden, and we had The Dog Who Smiled and Meant It: a one-year-old French bulldog named Blanche, a warm, soft little blond thing so bright, amiable, and mellow that I’d considered donating her chromosomes for research on the Biology of Nice.

Not that anyone was studying the topic. Dog doesn’t bite man is no story at all.

Milo’s ninth day back on the job, someone got bit.

It took place on one of those streets where that kind of thing doesn’t happen.

At six thirty-two a.m. on a quiet Sunday in a South Westwood neighborhood where small, tidy houses are dominated by the spire of the Mormon temple on Santa Monica Boulevard, a seventy-three-year-old retired schoolteacher named Ella Mancusi opened the door to her mint-green stucco bungalow, walked ten feet to pick up her newspaper, and came face-to-face with a man and a knife.

The sole witness, an insomniac advertising copywriter named Edward Moskow, was drinking coffee and reading his own paper in his living room, two houses south. By chance, he looked out the window, saw what he thought was a man punching Ella Mancusi, watched in horror as the old woman crumpled into a pool of blood.

By the time Moskow reached Ella, she was dead and her murderer was fleeing the scene.

The coroner’s investigator counted nine stab wounds, four of them fatal. From the depth and width of the cuts, the on-the-scene guess was a hefty, nonserrated, single-edged blade, consistent with some kind of hunting knife.

Most remarkable was Moskow’s description of the killer: a tall, heavyset, white-haired man wearing dark, baggy clothes and a blue plaid cap.

“One of those old-guy caps, he was a geezer. When he walked to his car, he moved stiffly, like old guys do.”

The car had been left idling at the curb, driver’s door open, as the man in the cap butchered his victim. Once finished, he wiped the blade on a trouser leg, got back behind the wheel, and drove off at a moderate rate of speed.

Moskow’s eagle eye extended to the vehicle.

“Late-model Mercedes S600, black, shiny and clean. It’s their top-of-the-line four-door if you don’t count the Maybach. I’m sure of it because I’m a car freak. We’re talking a bill and a half. I only caught part of the license plate.”

One letter, three digits. Milo put a trace on the vehicle before he went out to inspect the scene. By the time he called me, a hit had come through.

“Lifted from the Prestige Rent-A-Car lot in Beverly Hills, returned before they opened at nine. Company didn’t even know it was missing till I called. Odometer says forty-three miles were put on.”

“Was the lot locked?”

“Supposedly there’s a chain.”