A convicted killer, Luke Talbot, has always proclaimed his innocence and the team start to review the case against him, which appears uncertain. While still going through the serious business of growing up at university, the students search for new evidence which could set him free. Nick also finds himself on the wrong side of the criminal justice system – which could mean the end of his legal career before it's even started.
Beth tries to convince an apparently unenthusiastic Ford about the merits of a case in which the infallibility of fingerprint evidence comes under scrutiny. Vulnerable Martin Toal retracted a confession of murder, even though his fingerprints were found at the crime scene. He's now serving life. Beth believes the system has let Toal down. Adam is mentoring a young boy, Dizzy - but trying to overturn his ASBO is loaded with difficulty. With her mother putting extra pressure on her, Beth finds herself with more on her plate than she can handle.
Adam tries to understand how a murder conviction can be beyond reasonable doubt – when there is no body. John McKenna may have been convicted of murdering his common-law wife, but her body has never been found. Meanwhile, Ford makes Nick struggle with a case that is over 300 years old – an attempt to prove the innocence of a woman who was executed as a witch.Sarah is caught off-guard when her boyfriend from home, Craig, turns up with an unexpected proposal.
The students tackle the complex ramifications of a joint trial: co-defendants who were tried together and both convicted of murder. The team hit a wall when they attempt to analyse what evidence the jury ultimately based their guilty verdict on. Beth is appalled by the injustice and wants to approach the jury. But Ford lays down the law – such an approach would be illegal. Sarah and Nick get sidetracked by a case involving an adult website and just what obscenity means in this day and age.
An old face appears from Ford's past, asking for help, but Ford's not so sure he wants to get involved. The students attempt to help a convicted drug dealer get her sentence reduced. Rhiannon Hayes was convicted of selling drugs to an undercover policeman – but were the police more than just a willing buyer? Adam is forced to question his idealistic viewpoint when he fears Dizzy may have betrayed him.
A convicted murderer claims that rather than killing the victim, all he actually did was try and help. The students put expert evidence under the microscope. When Sarah and Beth get involved in a case the CPS passed over, Beth finds herself working for the other side with PC Todd, with unexpected rewards. Ford can't seem to shift the piles of work on his desk but has a good reason for taking so much on.
The students are put to the test by the different claims and counter claims in a rape case. A notoriously difficult offence to get a conviction for - they wonder if it's something they should even be looking at. Ford is stumped when Sarah and Andrew want to discuss how to prove a retired police dog was an unreliable witness.
The team struggle to prove that a murder case was, in fact, a suicide. Adam gets involved in the mechanics, while the others investigate the victim's state of mind. Ford may know more about the drugs which might have contributed to the victim's death than he's letting on. So he finds himself with several difficult decisions to make - both personally and professionally.