Once or twice he started forward, as if on the point of sneaking in, but thought better of it and retreated.

Once his attitude suggested that he might be taking aim with a pistol; but if that was so, he chose not to waste a shot or start an alarm by firing at a mark he couldn't see.

What he did accomplish was to keep six keen eyes fixed on him.
And that gave three other men their chance to gain an entrance at the rear of the wall in the garden, and creep up unawares.

It was probably sheer accident that led all three of them along the far side of the house, but it was fortunate for Jeremy and me, for otherwise cold steel between our shoulder-blades would likely have been our first intimation of their presence.
We never suspected their existence until they gained the veranda by the end opposite to where we waited; and I think they would have done their murder if the man outside the gate hadn't lost his head from excitement, or some similar emotion and tried to make a signal to them.

All three had brought up against the end window, where a shade torn in two places provided a good view into the room in which Grim, Mabel and the doctor were still sitting.