Have you ever smelled a particular fragrance, and the memories associated with that particular smell came rushing back to you like a tidal wave? You're most certainly not alone, and there is real science out there that links our olfactory system with memories.
New smells that are detected by the brain travel along nerves that are processed by the olfactory bulb. This interesting little bundle of nerves sits at the front of the brain and is closely linked to both emotion and memory. What is most insightful about this is the fact that our other senses like audio and visual aren't linked to emotion and memory. This explains why watching an old movie might not necessarily trigger the same emotions as smelling fresh baked apple pie and linking it with Thanksgiving, for example.