Mother Leanne Wellings disappears while buying flowers from a van parked off a highway, leaving her young son and daughter alone. By the time police have been notified, the two children have also disappeared, triggering a desperate search led by Detective Iain Barclay.

Barclay and his team pursue their leads as press officer Defne Topcu arranges a press conference. A worker at the retirement home suspects her son may have been involved in the abduction and calls the police. Another breakthrough occurs when the flower seller is found.

Barclay has turned Leanne's disappearance into a murder investigation and Kyle Betts is the prime suspect. Matt, monitored by a marine buddy who's agreed to be an informant, discovers Leanne bought a one-way flight to France a matter of days before her disappearance.

Matt finds himself in a riff with Leanne's parents after he gives an interview at home with a TV crew. Later, Matt and Sarah spend the afternoon at a local fair and road race in a park, which ends with a grisly discovery - taking the family on another emotional ride.

The discovery of a burnt-out van offers fresh evidence to Barclay's team, and the police stakeout the home of Betts. Despite celebrating her retirement, Amy's work on the case isn't over - several new clues bring her and Barclay to the verge of finally solving the case.