It had been run by a firm that was buildin' some new kind of marine motors, but had gone broke. Used to be a stove works, I believe.

Anyway, it's only a two-story cement-block affair, jammed in between some car-barns on one side and a brewery on the other. Hot proposition to trot out as the big end of a six-million-dollar contract! But it was the best I had to offer, and after the Lieutenant had finished his Oolong and lighted a cigarette I loads him into the limousine again and we shoots uptown.

"Here we are," says I, as we turns into a cross street just before it ends in the East River. "The main works," and I waves my band around casual.

"Ah, yes," says he, gettin' his eye on the tall brick stack of the brewery and then lettin' his gaze roam across to the car-barns.

"Temporary quarters," says I. "Kind of miscellaneous, ain't they? Here's the main entrance. Let's go in here first." And I steers him through the office door of the middle buildin'. Then I hunts up the superintendent.

"Just takin' a ramble through the works," says I. "Don't bother. We'll find our way."

Some busy little scene it is, too, with all them lathes and things goin', belts whirrin' overhead, and workmen in undershirts about as thick as they could be placed.

I towed Cecil in and out of rooms, up and down stairs, until he must have been dizzy, and ends by leadin' him into the yard.

"Storage sheds," says I, pointin' to the neat rows of shell-cases piled from the ground to the roof. "And a dozen motor-trucks haulin' 'em away all the time."

The Lieutenant he inspects some of 'em, lookin' wise; and then he walks to the back, where there's a high board fence with barbed wire on top. "What's over there?" says he.

"Blamed if I know," says I.

"It's rather important," says he. "Let's have a look."

I didn't get the connection, but I helped him shove a packin'-case up against the fence, so he could climb up. For a minute or so he stares, then he ducks down and beckons to me.

"I say," he whispers. "Come up here. Don't show your head. There! What do you make of that?"

So I'm prepared for something tragic and thrillin'. But all I can see is an old slate-roofed house, one of these weather-beaten, dormer-windowed relics of the time when that part of town was still in the suburbs. There's quite a big yard in the back, with a few scrubby old pear trees, a double row of mangy box-bushes, and other traces of what must have been a garden.

In the far corner is a crazy old summer-house with a saggin' roof and the sides covered with tar paper. There's a door to it, fastened with a big red padlock.

Standin' on the back porch of the house are two of the help, so I judged. One is a square-built female with a stupid, heavy face, while the other is a tall, skinny old girl with narrow-set eyes and a sharp nose.

"Well," says I, "where's your riot?"

"S-s-s-sh!" says he. "They're up to some mischief. One of them is hiding something under her shawl. Watch."

Sure enough, the skinny one did have her left elbow stuck out, and there was a bulge in the shawl.

"Looks like a case of emptyin' the ashes," says I.

"Or of placing a bomb," whispers the Lieutenant.

"Mooshwaw!" says I. "Bomb your aunt! What for should they—"

"Look now!" he breaks in. "There!"

They're advancin' in single file, slow and stealthy, and gazin' around cautious. Mainly they seem to be watchin' the back fire-escapes of the flat buildin' next door, but now and then one of 'em turns and glances towards the old house they've just left. They make straight for the shack in the corner of the yard, and in a minute more the fat one has produced a key and is fumblin' with the red padlock.

She opens the door only far enough to let the slim one slip in, then stands with her back against it, her eyes rollin' first one way and then the other.

Two or three minutes the slim one was in there, then she slides out, the door is locked, and she scuttles off towards the house, the wide one waddlin' behind her.

"My word!" gasps the Lieutenant. "Right against the wing of your factory, that shed is. And a bomb of that size would blow it into match-wood."

"That's so," says I.

Course, we hadn't really seen any bomb; but, what with the odd notions of them two females and the Lieutenant's panicky talk, I was feelin' almost jumpy myself.

"A time-fuse, most likely," says he, "set for midnight. That should give us several hours. We must find out who lives in that house."

"Ought to be simple," says I. "Come on."

We chases around the block and rings up the janitor of the flat buildin'. He's a wrinkled, blear-eyed old pirate, just on his way to the corner with a tin growler.

"Yah! You won't git in to sell him no books," says he, leerin' at us.

"Think so?" says I, displayin' a quarter temptin'. "Maybe if we had his name, though, and knew something about him, we might—"

"It's Bauer," says the janitor, eyein' the two bits longin'. "Herman Z. Bauer; a big brewer once, but now—yah, an old cripple. Gout, they say. And mean as he is rich. See that high fence? He built that to shut off our light—the swine! Bauer, his name is. You ask for Herman Bauer. Maybe you get in."

"Thanks, old sport," says I, slippin' him the quarter. "Give him your best regards, shall I?"

And as he goes off chucklin' the Lieutenant whispers hoarse:

"Hah! I knew it. Bauer, eh? And to-night he'll be sitting at one of those back windows, his ears stuffed with cotton, watching to see your plant blown up. We must have the constables here right away."

"On what charge?" says I. "That two of the kitchen maids was seen in their own back yard? You know you can't spring that safety-of-the-realm stuff over here. The police would only give us the laugh. We got to have something definite to tell the sergeant. Let's go after it."

"But I say!" protests Cecil. "Just how, you know?"

"Not by stickin' here, anyway," says I. "Kick in and use your bean, is my program. Come along and see what happens."

So first off we strolls past and has a look at the place. It's shut in by a rusty iron fence with high spiked pickets. The house sets well back from the sidewalk, and the front is nearly covered by some sort of vine. At the side there are double gates openin' into a grass-grown driveway.

I was just noticin' that they was chained and locked when the Lieutenant gives me a nudge and pulls me along by the coat sleeve. I gets a glimpse of the square-built female waddlin' around the corner of the house. We passes by innocent and hangs up in front of a plumbery shop, starin' in at a fascinatin' display of one bathtub and a second-hand hot-water boiler. Out of the corner of my eye, though, I could see her scout up and down the street, unfasten the gate, and then disappear.

"Huh!" says I. "Kitchen company expected."

"Or more conspirators," adds Cecil. "By Jove! Isn't this one now?"

There's no denyin' he looked the part, this short-legged, long-armed, heavy-podded gent with the greasy old derby tilted rakish over one ear. Such a hard face he has, a reg'lar low-brow map, and a neck like a choppin'-block. His stubby legs are sprung out at the knees, and his arms have a good deal the same curve.

"Built like a dachshund, ain't he?" I remarks.

"Quite so," says Fothergill. "See, he's stopping. And he has a bundle under one arm."

"Overalls," says I. "Plumber, maybe."

"Isn't that a knife-handle sticking out of the end of the bundle?" asks the Lieutenant.

So it was; a butcher knife, at that. He has stopped opposite the double gates and is scowlin' around. Then he glances quick at the house. A side shutter opens just then and a dust-cloth is shaken vigorous. Seein' which, he promptly pushes through the gates.

"Ha!" says the Lieutenant. "A signal. He'll be the one to attach the fuse and light it, eh?"

Well, I admit that up to that time I hadn't been takin' all this very