We have all had the embarrassing experience of seeing an acquaintance in an unfamiliar setting. We know we know them but can't recall who they are. But with the correct cues from conversation or context, something seems to click and we can readily access very rich and vivid memories about the individual. Researchers have shed some light on this mysterious process, discovering that the hippocampus, a brain region in the temporal lobe, is only involved when cues enable us to recall these rich memories.