Martha Costello is now a QC, but she learns fast that it can be lonely at the top. At Shoe Lane Chambers times are tough, and senior clerk Billy struggles to keep things afloat while Clive Reader tries to be stoic about his unsuccessful silk application. Martha is defending Brendan Kay, a member of one of London's biggest crime outfits. He is accused of blinding a man, who allegedly disrespected their 'number two'. Martha's job is made harder because Brendan's solicitor, Micky Joy, is an old school player of the system who walks both sides of the line. Also up against a notorious QC, Caroline Warwick, nicknamed Lady MacBeth for her uncompromising approach in court, Martha feels herself pulled by the various political forces around her, and realises to win she will need an all or nothing defence. Meanwhile, Clive takes on a sensitive case with a new solicitor, George Duggan.

Martha represents Captain Ed Ryan in a court-martial. He is accused of disobeying an order, resulting in the death of a 19-year-old private. Under the watchful eyes of a distraught family who want answers, Martha navigates the army's legal system with the help of Captain Cassidy, Ryan's unit defence officer. Doggedly seeking the truth, Martha slowly peels back the layers of past and present wounds, revealing the shocking reality of modern combat.

Meanwhile, temptation is never far away for Clive, who is warned by Billy to keep his relationship with George Duggan purely professional.

Clive is in Oxford, prosecuting three students accused of sexually assaulting a waitress. Up against an intimidating defence counsel, Clive begins to waver, but a chance encounter with an old friend helps him discover a passion for prosecuting he did not know he had. When the case is in danger of collapsing, Clive is faced with one of the biggest decisions of his career.

Meanwhile, Martha is defending Ricky Armitage, who trashed his local mini-mart and attacked the shopkeeper. His level of violence and lack of remorse is astounding, yet Martha tries to divert the self-destructive path that Ricky was fated to walk.

At the Supreme Court, Martha is representing Jackson Henderson in a death row case. Against a ticking clock and with Billy breathing down her neck, Martha faces the toughest legal argument of her career.

Clive increasingly feels that he is not the right barrister for Fatima Ali and, at the risk of losing George, persuades Martha to take the brief, conveniently leaving him free to prosecute Jody Farr.

Martha knows unless Fatima speaks up for herself, the truth will not surface. Just as she thinks the case is lost, Martha is offered a deal with the devil in return for Fatima's freedom.

Reluctantly representing Jody Farr, Martha vows to do her job, but she will not allow him or Micky to get under her skin. Fighting shifting power plays and an untenable defence, she begins to feel that Jody is not getting a fair trial and suspects foul play. Setting a dangerous trap, can Martha uncover the unbelievable truth?

With the date of his tribunal looming, Clive focuses all his efforts on prosecuting Jody Farr, despite the apparent lack of support from CW. In the face of an uncertain future, Billy finds himself trapped by Micky Joy and loyalties are stretched to breaking point.