Should you tell a child that his mother is dying of cancer? Should you pretend that all will be well, when you know that it won't? A Monster Calls is a powerful play about a 13-year-old who knows he - who is closer to his mother than anyone - is being left to deal with oncoming grief alone. When director, Sally Cookson read the novel A Monster Calls by Patrick Ness she says: "I read the book in one hit. "I thought I would kill for the opportunity to make this story into a piece of theatre." Her staging of the story is about to tour and will be at Cambridge Art Theatre from March 24-28 and is likely to become a hot ticket. Her previous critically acclaimed hits include La Strada, a stage version of Fellini's 1954 film, co-produced by Cambridge Arts Theatre in 2017. That show received rave reviews - as total theatre with drama, physical theatre, humour and tragedy. The story of A Monster Calls circles round 13-year-old Conor. His mum, a single parent, is dying of cancer but no one else in the family will say she is dying. They keep saying she will be all right. She won't be. He knows she won't be and this hiding of the truth isolates him. It will mean that when she does die, he will be unprepared for it and meanwhile, he has no one to express his fears or his feelings to. He is having to pretend along with the rest of them. But all the time, he is anticipating a grief. Into this chasm comes a helpful monster - a tree that Conor can talk to and who speaks to him. They tell each other powerful stories. Stories are wild creatures, the Monster says. When you let them loose, who knows what havoc they might wreak. But when the roof caves in, it allows in the light. With a tragic irony, the book, written for young adults, did not start with its author Patrick Ness. It was the idea of Irish writer Siobhan Dowd. She had written four award-winning novels and Waterstones had just named her one of the top 25 authors of the future when she died of cancer in April 2007, aged 47. Ness was invited to finish A Monster Calls and later to adapt it for the screen. The book has sold over a million copies. The play won last year's Best Entertainment and Family Olivier Award. The plot finds Conor, aged 13, tormented both at home and at school. His dad doesn't understand, his grandma won't stop interferring and there are school bullies. This production, created by The Old Vic in London in association with the Bristol Old Vic, has a forceful cast including 25-year-old Ammar Duffus, playing Conor with all the vunerability of a 13-year-old. He is so shocked at what is happening at home that, as the actor says, the school bullying is almost a relief because it's a distraction. "The bullying is normal for him," says Duffus. "It becomes a routine and his stoicism about that hides how he is actually feeling. While he is dealing with that can put aside what is happening at home." Conor withstands the bullying and doesn't react. Says Duffus: "He thinks if he doesn't respond, it won't get any worse." The Monster arrives outside Conor's bedroom window in the form of a massive tree. On stage, the enveloping branches are represented by ropes. The role demands a high degree of athleticism and the actor playing the creature, Keith Gilmore, has a background in dance. But is not the Monster that is scary. What the grown ups are scared of is the truth. Gilmore said: "Conor tells the Monster the truth - the truth makes them equals. Conor wants to know what is happening to his mum, he believes he has a right to know, because he is there for his mum like no one else is. The Monster tells Conor four tales, parables to help him and then Conor tells the Monster his own tales. Says Duffus: "The Monster makes Conor realise that it's ok to feel the way he does. No one has told him that." It's a powerful story and a strong piece of theatre. The book has been published in 43 languages and the play is suitable for children aged 10 upwards. It has an international resonance and is due to go to the Kennedy Centre in Washington this summer. Shows at Cambridge Arts Theatre will be at 7.45pm with matinees 2.30pm on Thursday and Saturday. Tickets 01223 503333 or www.cambridgeartstheatre.com.