The 1980s: Ten-year-old Kate Meaney - with her 'Top Secret' notebook and Mickey her toy monkey - is busy being a junior detective.
She observes goings-on and follows 'suspects' at the newly opened Green Oaks shopping centre and in her street, where she is friends with the newsagent's son, Adrian.
But when this curious, independent-spirited young girl disappears, Adrian falls under suspicion and is hounded out of his home by the press. Then, in 2004, Lisa is working as a deputy manager at Your Music, a cut-price record store.
Every day, under the watchful eye of the CCTV, she tears her hair out at the behaviour of her customers and colleagues.
But when she meets security guard Kurt, she becomes entranced by the little girl he keeps glimpsing on the centre's CCTV.
As their after-hours friendship intensifies, they investigate how these sightings might be connected to the unsettling history of Green Oaks.