In her latest novel, The Murder Rule, McTiernan turns to her fascination with the experiences of a young Irish law student Niamh Gunn, who spent a summer in the US volunteering for the Innocence Project, trying to free Walter Swift, from prison. Gunn eventually managed to persuade a retired policeman to tell the truth about evidence that had been hidden in the original prosecution. Walter Swift, after 26 years in prison, was freed.

McTiernan has said that The Murder Rule was the result of her thinking about "doing such impossibly challenging work in a world which is so loud, and messy and unwilling to listen or help."

The novel is set in Maine, where McTiernan herself worked as a law student, drawing on her memories, which she claims are "among my brightest and most tightly held".

Young Law student Hannak Rokeby transfers to the University of Virginia specifically to volunteer for the Innocence Project, headed by Professor Parekh, telling him in her application, "I passionately believe in the work you do . . . and I would be so grateful to be given the opportunity to work for a cause what is so close to my heart".

Hannah, however, doesn't tell Parekh her true motivations, which are connected to her alcoholic mother Laura's troubled past. Hannah quickly impresses both Parekh and his team of student lawyers with her diligence and creative ideas and she is cop-opted to work on the case of Michael Dandridge, who was convicted of the murder of Sarah Fitzhugh in 2008.

He has already served 11 years of his sentence on death row, but has always claimed he has been the victim of a gross miscarriage of justice.

Working on the Dandridge case has been Hannah's objective all along. However, she is not interested in proving his innocence but rather in ensuring he is never released.

McTiernan needs her readers to suspend their disbelief in the dramatic second half of her story, particularly in the final court scene.

Nonetheless, The Murder Rule is an intriguing novel about secrets and lies, and the moral consequences of deception. As a result, the FX Network in the US has already optioned the novel for a TV series.