Still I managed to rake up the pluck to set my teeth and choke back the horrid doubts that flooded in on me.

I simply shut off my mind and pretended I was doing an experiment as simple as Guy Fawkes fireworks.
I got a detonator, and fixed it to a couple of feet of fuse.

Then I took a quarter of a lentonite brick, and buried it near the door below one of the sacks in a crack of the floor, fixing the detonator in it.
For all I knew half those boxes might be dynamite.

If the cupboard held such deadly explosives, why not the boxes?
In that case there would be a glorious skyward journey for me and the German servants and about an acre of surrounding country.

There was also the risk that the detonation might set off the other bricks in the cupboard, for I had forgotten most that I knew about lentonite.