I'd be inclined to look for hidden wires and burning arrows.

They came from a metal plate beneath it, where Leboux had attached hidden wires.

A few hidden wires and cans could cover the house and barn.

She was propped up against a support that day, held erect with hidden wires because she was too weak to stand on her own.

Either way, pulling on the hidden wire triggers detonation.

Yet another bullet point in their plan, he noted as he clipped a phone company dial set across the pair of hidden colored wires.

Additional small fires raced across the hidden wires within the fabric.

At the same time, much of their illegal business was recorded by hidden wires on the newly-made turncoat.

He went down exactly as if he had tripped over a hidden wire.

He peered at the makeup of the cube itself, searching for hidden wires or magnets.