Call The Midwife's sixth series has seen Sister Mary Cynthia (Bryony Hannah) going through a very tough time indeed.

In the first episode the young nun broke down as she struggled to come to terms with the violence she was exposed to when visiting a young mum with an abusive husband.

The incident set in motion a harrowing chain of events, which culminated in the young nun's disappearance from Nonnatus House. 

Where did Sister Mary Cynthia disappear to?

In series six episode one Doctor Turner was called to Nonnatus House to try to establish the correct diagnosis and course of treatment for his colleague and friend.

However, before he could recommend that she be sent to a sympathetic community - Northfields - to help her recover, Sister Ursula had Mary Cynthia shipped off to the Mother House in the dark of night.

For weeks we wondered how she was doing, especially when Trixie revealed she hadn’t seen her at the Mother House on her way home.

And then in episode five, Fred and Sister Monica Joan discovered her in a locked room at the Linchmere Hospital, a mental health institution.

Sister Mary Cynthia had been sent there to recover, but she seemed anything but better. In fact, she seemed in a worse state than she had been when she left Nonnatus House.

In episode six we saw her return to her spiritual home, seemingly on the way to making a full recovery, but it wasn't long before her friends and colleagues realised that all was not well.

She ultimately departed for Northfield after all, where she was welcomed under her own name - Cynthia.

What happened to Sister Mary Cynthia when she was attacked in series five?

In series five episode six you might recall a plot involving several women being attacked by an individual who left a bite mark on their neck. Well, Sister Mary Cynthia fell victim to that same attacker.

While cycling back to Nonnatus as the sun rose, she stopped by the docks for a moment of contemplation. It was there that she was attacked, waking up bloodied and beaten. She returned to Nonnatus where a shocked Trixie rushed to help her.

"Please don't touch me," Mary Cynthia screamed. It was established that she wasn't raped, but she had been viciously attacked – and had a bite mark on her neck. 

"Don't talk to me gently, don't be kind, because I'm angry," she told Sister Julienne, refusing to be examined by a doctor or talk to PC Noakes initially, before eventually changing her mind and providing evidence that led to the apprehension of her attacker.

Will Sister Mary Cynthia return to Call The Midwife?

"Her journey does continue later in the series. No spoilers - but you do find out how she’s doing, how she’s getting on", writer Heidi Thomas told RadioTimes.com after her initial departure.

"[Bryony Thomas] is a wonderful actress and I absolutely loved writing that material for her. Because she’s also a character that’s been with us from the very beginning" she continued. "She had the trauma in series 5 when she was attacked and she seemed to get over that quite quickly but I already knew that she hadn’t fully dealt with that experience and therefore it was actually not just dramatically interesting but also really emotionally responsible to show what she went through a few months later when she had to deal with what she hadn’t dealt with at that time."

"So we do continue with that journey, Bryony gives the most sensational performance."

It remains to be seen whether the journey will continue into series 7, but we're hopeful that this isn't the last we've seen of Bryony Hannah at Nonnatus House.