Lullaby: Part 1 is the 1530th episode of The Bill.
PCs Rickman and Smith catch a 7-year-old Chinese boy named Tim Tze breaking into his school late at night. It emerges that he has been living on his own for three days, seemingly abandoned by his parents. When questioned, Tim is unable or unwilling to say what has happened to them.
As the investigation continues, DI Deakin and DC Lennox discover blood under the carpet at the house; forensics reveal that the blood under the carpet came from two different people, a man and a woman. DC Glaze and DC Webb's examination of a nearby CCTV camera shows a van had been parked outside the Tzes' house for an unusually long time. The van is traced to Peter Burton, who a week earlier had been involved in an allegedly racially-motivated disturbance at the Chinese restaurant where Tim's father works.
It turns out the officer who attended that call was Smithy, and Deakin is furious at him for not following up on the racism accusations against Burton. Smith insists that he did report it to Deakin, and that he didn't feel the matter worth pursuing. When questioned, Burton denies knowing the Tzes or attacking the staff at the restaurant the week before, instead countering that one of them attacked him with a butcher's knife.
The investigators find out that someone has been making phone calls to the Tze house, but Deakin is unable to get more information from Tim, who appears anxious to return home, as if expecting someone to call at the house. However, Tim tells Smith that he saw a man outside the house, and that the same man had previously had an argument with his father at the front door and tried to enter their home. At a line-up, Tim identifies Burton as the man who was outside the house.
Continued in Lullaby, Part 2.