in the Night-Time, adapted the play from the book of the same name by Mark Haddon. In an interview, Stephens talks about the big differences between plays and books, and how his understanding of these differences affected how he presents the story and its main character, Christopher.

[T]he difference between the book and the play is the play concerns itself with behavior and the novel with observation or thought.

In both book and play, Christopher is a young man on the autism spectrum, with Asperger’s syndrome. He is a math genius but socially awkward, preferring to live his life based on the strict rules he has created as a result of his Asperger's. He cannot stand being touched by others; he loves animals and is very gentle with them; he has strong aversions to certain colors, smells, and tastes; he invents and plays private games that tell him what kind of day it is going to be, such as his game of identifying the color of the first car he sees on the street in the morning.

At the very start of the novel, and the play, Christopher discovers that his neighbor's dog has been mysteriously killed with a gardening fork. This is the first incident of loss in the story. In the book, Christopher narrates the tale in first person as he writes his own book about his story. In the play, his friend and counselor from school, Siobhan, reads aloud (and to us) from Christopher’s novel, as we watch him discover the dog onstage:

Christopher puts his hands over his ears. He closes his eyes. He rolls forward. He presses his forehead onto the grass. He starts groaning.

SIOBHAN: "After twelve and a half minutes a policeman arrived. He had a big orange leaf stuck to the bottom of his shoe which was poking out from one side." This is good Christopher. It’s quite exciting. I like the details. They make it more realistic.

Playwright Stephens presents layers of experience and story here. We hear Christopher writing about the experience later and see how observant he is, but at the same time we watch him feeling intensely upset in the moment. He loved his neighbor’s dog, and finding it dead is understandably extremely stressful. This is a complex portrait of how the young man deals with loss: he distances himself from the stress of emotion by rolling on the ground and groaning, but at the same time, he is aware enough to notice tiny details such as the leaf on the policeman’s shoe.

For both reasons—his strong logic and hyper-accurate attention to details, and his love for the dog—Christopher decides to investigate the dog’s death and find out who did it. His attempt to solve this mystery leads Christopher into the heart of an even deeper mystery and even more intense feelings of loss and rejection.

Christopher believes his mother, Judy, is dead. His father, Ed, has told him she got sick, went into hospital, and then died. But the truth is that Judy became overwhelmed with having an autistic son, and thanks to that and her escalating fights and mutual infidelity with Ed, she left their home and moved to London. Rather than dealing with the truth, Ed has lied to his son about it. It turns out that the woman Ed had an affair with was their neighbor, Mrs. Shears. After an intense argument, Ed became blind with anger, and while her dog was yapping, the “red mist came down": he killed the dog.

All together, this is too much for Christopher:

Ed leaves. Christopher groans. He starts counting.

CHRISTOPHER: 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16,384, 32,768, 32,768, 32,768—

SIOBHAN: Father had murdered Wellington. That meant he could murder me.

I had to get out of the house.

I made a decision. I did this by thinking of all the things I could do and deciding if they were the right decision or not.

ED: Stay home.

SIOBHAN: I decided I couldn’t stay home anymore.

Again, Stephens presents loss and rejection in complex layers of performance. Christopher recites a number sequence to try and calm down after receiving all of this surprising and frightening news. He reasons—as Siobhan reads later from his book—that he could be murdered, because his father is a murderer. It is clear that he is upset about the revelations about his mother and about the dog, and he chooses to go to 451c Chapter Road, London, NW2 5NG. This is the address on the envelope of a letter Judy has written to him—a letter he has only just discovered today, as Ed has kept it hidden from him.

Though Judy rejected Christopher when she left, he clearly wants and needs to see her. The very simple stage direction at the end of part 1 of the play, as Christopher recites the London address over and over, is

Christopher looks at Judy.

This moment is not happening in “real time,” but it evokes the shared emotions between the separated mother and son, and it points toward their journeys toward one another in the second part of the play.

When he is faced with loss and rejection, Christopher’s reactions and behaviors allow the actors to fill their performances with emotions that we will recognize and be moved by. All Stephens has to write is "Christopher looks at Judy" at the climax of the first act, and we know that Christopher is about to make a brave and frightening choice to find his mother in London, even if he is unable to articulate why he needs to do this. As Stephens has said,

I think characters are sympathetic not because of what they say but because we recognize within them desire. What breaks our heart in drama is when a characters’ desire is clear and specific and that pursuit of that desire is determined and brave. What makes people cry in the theatre is bravery, its people being brave.

It's never explicitly spelled out exactly what Christopher's condition is, but it shows all the hallmarks of autism. That being the case, Christopher, as with many people on the autistic scale, finds it difficult to recognize emotions or indeed develop typical emotional responses. Inevitably, this makes it difficult for those with autism to interact with others.

Christopher can identify a list of behaviors normally associated with love, but love itself, at least the way others see it and experience it, remains largely an alien concept for him.

Although Christopher is shown love by his parents, he is unable to reciprocate. As with many autistic people, he is deeply uncomfortable with being hugged. This means that father and son are restricted to showing affection for each other by holding up the palms of their hands and touching fingertips. Even then, it's far from clear that Christopher truly comprehends the full meaning of this affectionate gesture.

The nearest that Christopher comes to showing love is when he hugs the dead dog Wellington. As Wellington is a dog, and a dead dog at that, physical contact with him doesn't represent any kind of threat to Christopher.

His affectionate gesture toward the deceased animal could be interpreted as an expression of love, however modest. One could also say that Christopher's determination to find out who killed the dog, as well as expressing his penchant for problem-solving, is also motivated by some kind of love for Wellington.

The Curious Incident of the Dog in the Night-Time revolves around Christopher, who is a young autistic savant. Christopher is frequently baffled and frustrated by types of thinking that aren't formulaic or dictated by logical reasoning, and he prefers the concrete problem-solving that occurs in the worlds of math and science over confusing abstractions like the concept of love, which is difficult to grasp for him.

Christopher has developed a list of clear factors that may evidence the presence of love, but he does not understand the actual feeling that is described in writing and the everyday happenings around him. He often contemplates the love of his father and cannot reconcile his actions as being motivated by what people call love. One level on which Christopher has seemingly felt love is his attachment and fixation with animals, as the entire narrative revolves around him obsessing over who is responsible for the death of a dog.