"Would it not be advisable, Inspector," I asked excitedly, "to make
sure of her at once?"

Gatton smiled grimly, and:

"Marie would have to make herself invisible to evade Scotland Yard
now," he replied. "She is being watched closely. But," he continued,
"what do you make of these marks on the door?"

We had reclosed the garage door and now were standing immediately
inside. The marks to which my companion had drawn my attention were
situated high up near the roof.

"This may account for the statement of Bolton that the door seemed
more difficult to open last night than to-day," he said. "Unless I am
greatly mistaken, some sort of attachment existed here until quite
recently."

"Possibly a contrivance for reclosing the door?" I suggested.

The marks in fact roughly corresponded to those which would be made by
the presence of such a contrivance and there seemed to have been some
attempt where it had been removed to disguise the holes left by the
screws.

"But the purpose of it?" muttered Gatton helplessly.

"God knows," I said; "the purpose of the whole thing is a mystery
beyond me entirely."