Tonight's topic is fear - inside Marijuana Anonymous
Fifty people are crammed into a small, hot, tense and brightly lit room in London discussing fear.
All of them are taking it in turns to open up about their lives and their addiction to cannabis.
For most of the people in this room this is a weekly event. It all feels normal. Painfully normal.
Newsbeat was given exclusive access to Marijuana Anonymous (MA). There are 10 groups in the UK and Dublin and Cork in the Republic of Ireland.
It begins with everyone introducing themselves by their first name and admitting they have a problem.
"My name is Lee and I'm a weed addict...", "My name is John and I'm an addict..." and so it goes on.
Some people have done this hundreds of times before. Some seem to find it very difficult - especially for those talking about the start of their battle with addiction.
The leader of the group speaks briefly about the 12-step programme and shares his story of addiction.
Then a topic for discussion is pulled out of a hat. Tonight it's "fear".
It gets pretty dark and intense. Fear of the unknown, fear because of paranoia, fear of failure and fear of relapse.
Lee helps run the group - he's an addict of more than 20 years. He tells me that "a lot of people find that fear is a big part of addiction.
"Fear is really one of the driving forces behind substance abuse."
There's a surreal moment when one of the members talks about being high and trying to find spiritual meaning in pattern of a carpet.
Lee says opening up and being really honest is one of the biggest issues for many people at the meeting.
"It can be overwhelming when you hear people talk so honestly about their feelings and what is going on in their lives.
"I think you get used to it. Sharing is a kind of group therapy, it's focussed on issues relating to the addiction and the problems living sober."
Some members have been coming here for years. They feel that if they don't keep coming back they will start smoking again.
John is 25 and had smoked cannabis for nine years before coming to MA. He tells me that his addiction will always be a big issue for him.
"I have a hole inside me that I tried to fill for my life and with weed that just fit the hole.
"It was the perfect match it filled all the gaps and that's why I went back to it. Now I fill that with MA."
Some of the people here have had their setbacks and Lee says it's not uncommon for people to fall off the wagon.
"It's not always easy. People relapse and people find that life on life's terms is very hard."
But Lee says failure was part of the process for some people and there was always help at MA when people needed it.
"The meetings are designed to be a safe place, that's why they are anonymous. It's the honesty that keeps us coming back."
If you need help with any of the issues mentioned head to the Radio 1 Advice pages..