It is Thomas Shelby's long-awaited wedding day. A mysterious visitor imperils the entire Shelby family, and Tommy finds himself pulled into a web of intrigue more lethal than anything he has yet encountered.
Tommy discovers the extent of the mission given to him and the extreme lengths his new paymasters are willing to go to in their quest for power. Meanwhile his own family's activities lead to escalating danger in Birmingham.
Responding to the Italians' actions, Tommy is set on a path of deadly vengeance that could take him to his darkest place yet, and threatens to splinter the family. Responding to the Italians' actions, meanwhile, as he makes plans for his mission on behalf of the Russians, he realises there is a traitor in his midst.
Tommy plans the arms robbery but Polly is troubled to think that he is about to kill Father Hughes and confesses to a priest. Meanwhile the Shelby women feel used and threaten to go on strike unless they are kept in the loop about events and given a cut of profits. Tommy enjoys sex with Tatiana, who shows her dangerous side, though he voices his suspicions to her regarding Hughes. However, thanks to Polly's confession he is arrested for plotting to kill him, beaten up and forced into an arrangement, giving him little choice but to betray the Russians to save his ...