Possible Clues:

• He torments criminal as very backward
• Clear kind of flask stowed inside, as far down as possible
• Flask placed in bag at the bottom
• Flask in bag, farthest down
• Bottom pocket filled by flask
• Flask going into bag as far down as possible
• Lowest catch sealing insulated container
• Lowest part of engine thermostat
• Lowest trap catching vacuum flask
• Lowest temperature one's no frills vacuum flask approaches