Angels at work for us

Corrie ten Boom wrote of a remarkable experience at the Nazi Ravensbruck prison camp:

Together we entered the terrifying building. At a table were women who took away all our possessions. Everyone had to undress completely and then go to a room where her hair was checked.
I asked a woman who was busy checking the possessions of the new arrivals if I might use the toilet. She pointed to a door, and I discovered that the convenience was nothing more than a hole in the shower room floor. Betsie [her sister] stayed close behind me all the time. Suddenly I had an inspiration, "Quick, take off your woollen underwear," I whispered to her. I rolled it up with mine and laid it in a bundle in a corner with my little Bible. The spot was alive with cockroaches, but I didn't worry about that. I felt wonderfully relieved and happy. "The Lord is busy answering our prayers, Betsie," I whispered. "We shall not have to make the sacrifice of all our clothes."
We hurried back to the row of women waiting to be undressed. A little later, after we had had our showers and put on shirts and shabby dresses, I hid the roll of underwear and my Bible under my dress; but I prayed, "Lord, cause Thine angels to surround me; and let them not be transparent today, for the guards must not see me." I felt perfectly at ease. Calmly I passed the guards. Everyone was checked, from the front, the sides, the back. Not a bulge escaped the eyes of the guard. The woman just in front of me had hid a woolen vest under her dress; it was taken from her. They let me pass, for they did not see me. Betsie, right behind me, was searched.
But outside awaited another danger. On each side of the door were women who looked everyone over for a second time. They felt over the body of each one who passed. I knew they would not see me, for the angels were still surrounding me. I was not even surprised when they passed me by; but within me rose the jubilant cry, "O Lord, if Thou dost answer prayer, I can face even Ravensbruck unafraid."