 Roger Smith acts as a negotiator in a city where everyone has lost their memories and keep it that way. When he isn t helping hostage situations, he s saving the day in a giant robot known as Big O. Although Roger has no idea why the "megadeus" (Big O) responds to his commands or why his butler seems to be a master at fixing the high tech machine, he starts to question the forgotten past after the events started by an unsual case involving an android called R Dorothy. While he and Dorothy begin a Henry Higgins/Eliza Dolittle style of friendship, villains and mysterious characters enter with clues leading up to something that may bring out an emotion Roger has tried to fight all of his known life - fear.