Making a Murderer is back picking up the stories of American convicts Steven Avery and Brendan Dassey.
The 10-part documentary was one of Netflix's biggest hits of 2015.
It followed the case of Steven Avery and his nephew Brendan Dassey, both convicted of murdering Teresa Halbach in 2005.
Both men claim they are innocent and a campaign to pardon them picked up hundreds of thousands of supporters.
In this series we follow the pair as they continue to try and get their convictions overturned and there is one new character we think you are going to love.
Kathleen Zellner has taken on Steven Avery's case, she is a fiercely intelligent and methodical lawyer who she says "lives for the impossible cases."
Her track record is hugely impressive, Zellner has one of the highest success rates for overturning wrongful convictions in the United States.
So who is this woman that wants to prove Steven Avery is innocent?
Kathleen Zellner is 61, and practises in Chicago where she founded her law firm in 1991.
Since then she has overturned the convictions of 19 men, including a man called Joseph Burrows who had been sentenced to death.
Kathleen Zellner won the case after convincing the real killer to confess.
She is the only trial lawyer in the United States who has won five multi-million dollar record verdicts in the span of just 11 months.
She will not represent someone she believes is guilty. In fact one of the first things she says to her clients is: "If you are guilty, I will do a way better job of finding out you are guilty than any prosecutor could.
"You would have to be an idiot to hire me and be proved guilty."
Many of Zellner's clients are pro bono, which means they do not have to pay legal fees because they have no or very little income.
It was after watching the first series of Making A Murderer, she decided she wanted to represent Steven Avery.
What you see on screen is a very hands-on lawyer.
She recreates crime scenes, carrying out countless experiments to prove or disprove the findings of previous examinations.
These would normally be carried out by junior members of staff of her law firm.
This was a dream for the documentary makers Laura Ricciardi and Moira Demos.
"Kathleen is not a lawyer who works from behind a desk," says Moira.
"She goes to the crime scene, she gets her hands on the evidence, she does experiments with world renowned scientific experts.
"What is fascinating about her process is that it is very unconventional and yet very scientific."
One of the first things she does is buy the same car that Teresa Halbach owned to examine if the prosecution were correct in their findings.
Teresa was last seen at Avery's property and her car was found there with blood stains matching his DNA.
It was a key piece of evidence in the prosecution of Steven Avery.
So she carries out various experiments on the car with her team rather than sending one of her juniors and waiting for the results.
Zellner believes she knows who killed Teresa Halbach and it's not Steven Avery, she is certain he is innocent.
"I have one goal and that's to overturn the conviction of Steven Avery," she says on the show.
"It does not matter how long it takes, what it costs or what obstacles we have to overcome - our efforts to win Mr Avery's freedom will never stop."
There is no doubt Zellner is captivating to watch on screen, the same as watching anyone who is at the top of their field.
"Kathleen was incredibly gracious," Laura explains.
"What is interesting about her and Steven's back story is that for a number of years Steven was pursuing Kathleen, they knew about her incredible track record.
"She has a very vibrant practise, she was very busy with other cases, years later one of her clients who she exonerated brought her attention to the show .
"She said that when she saw Steven Avery's reaction to the verdict at his trial, that really won her over and made her decide to take the case."
Steven Avery was wrongfully imprisoned for 18 years for sexual assault.
Many think he was set up by law officials in Manitowoc County, Wisconsin, who feared they faced a huge financial penalty over it upon his release.
But those officials have always dismissed the claims as conspiracy theory.
Making A Murderer Part 2 is now streaming on Netflix.