“The Guilty” unfolds across two distinct timelines – 2008 and present day – centering on DC Maggie Brand (Tamsin Greig), a detective grappling with both a heartbreaking case and profound personal challenges. When young Callum Reid vanishes after a neighbourhood barbecue, his parents, Claire and Daniel (Katherine Kelly and Darren Boyd), are plunged into desperate hope, clinging to the possibility of his return. Five years later, Arcadian Gardens carries a heavy shadow – forever marked by that devastating weekend. The community’s fabric was irrevocably damaged, particularly impacting Callum's older brother, Luke. But just as the anniversary of his disappearance looms, a chilling discovery reignites the nightmare: Callum’s body is found, shockingly close to home. Now, DCI Maggie Brand takes charge of the reopened investigation. Years earlier, debilitating illness had forced her off the original case while she was pregnant. Her son, Sam, born shortly after Callum's disappearance, is now beginning school, and Maggie finds herself navigating a complex blend of maternal anxieties and lingering grief as she observes his differences from other children. Driven by an unwavering determination to uncover the truth behind Callum’s fate, Maggie relentlessly pursues every lead, determined to unravel the events of that fateful night.