Sam was the owner of Sam's Sandwiches and provided deliveries to various locations. He became embroiled in sequence of events triggered by the Fourth Doctor. While driving his van, he sounded his horn to alert a cyclist who had stepped into his delivery bay.
Exiting his vehicle, he greeted Emma, causing her to blush, before entering an office building to make his delivery. When he came out again, he found her searching under his van for a coin. This led to a conversation that resulted in the two exchanging numbers and agreeing on a first date at an Italian restaurant. (AUDIO: Chain Reaction)