Sharon Duncan-Brewster, a Black actress, reprises the role of Moriarty (revealed as Mira Troy/Professor Adeline Rathe), a gender- and race-swapped version of the canonical male villain whose motivations in the prior film explicitly tied to revenge for systemic injustices; the third installment deepens this with her kidnapping Sherlock and political maneuvering in Malta. Himesh Patel, of Indian descent, plays Dr. John Watson, another established character race-swapped from the traditional white portrayal.

The central plot revolves around British colonial crimes, including stolen Afghan gold from the Battle of Khost transported to Malta, with Enola and Sherlock ensuring its return to Afghanistan as acknowledgment that 'it never belonged to Britain,' while Tewkesbury renounces his title and Lords seat upon learning of his father's imperial involvement. Writer Jack Thorne intentionally fictionalized these elements to explore 'the complication of empire' and Malta's colonial status.

Enola's wedding-to-Tewkesbury arc foregrounds female independence versus marriage in Victorian society as a recurring conflict. Audience and critic responses show mixed reception with a 69% Rotten Tomatoes score and complaints about formulaic execution, though without widespread 'go woke go broke' labeling; one analysis site scored it 4/10 on woke metrics, understating the centrality of the empire subplot.