"I love the idea of messing with people's minds, always have," he says. "If you write a pop song, you want to write one that people will sing along to; if you draw a picture you want it to evoke a certain mood. If I write a scary story, the fact that people are terrified is a compliment. Criticism is high praise."
His smile widens when I tell him how a scene from one of his novels, in which a woman's unborn baby is brutally sliced from her womb, almost made my lunch reappear. I'm not alone in my squeamishness: one reviewer said the 44-year-old was "capable of some of the most traumatising scenes you're ever likely to experience in a mainstream crime novel".
I imagine a stroll inside Cross' mind must be a little like wading though a fetid, undrained swamp.
"People always expect me to be some kind of madman, but the fictional violence is never a fantasy of what I'd like to do to someone else; it's more a way to face up to the fear of what someone might do to me. It's a function of fear."
And, oddly, happiness. "I love my family, my work and my life but there's always a part of me that worries about the worst that can happen. I think the really dark stuff comes more from being happy than unhappy. The greatest fear is having happiness taken away."
In person, on a warm May afternoon, the British-born writer is nothing like the characters he creates. He's funny, engaging, polite and, with his neatly trimmed goatee and black-rimmed glasses, looks more like an IT consultant than someone who spends his day dreaming up increasingly inventive ways for humans to kill and maim each other.
He's also a homebody who would gladly never leave the house he shares with Kiwi wife Nadya Kooznetzoff and sons Ethan (12) and Finn (10) in one of Wellington's most sedate suburbs.
"I like living in Crofton Downs precisely because it is so unfashionable. It's in my nature to be contrary, to do the opposite of what everyone expects."
There are, however, the markers of success: a newly built office filled with awards, late-model cars in the driveway, expensive artwork.
There's also tea - lots of it - served with biscuits and apologies: Cross had to push back our interview because he spent the morning taking conference calls from Hollywood for his latest project, Crossbones, a 12-part television series featuring John Malkovich as Blackbeard. ("We were lucky to get Malkovich because he never does TV.")
The man named as one of Variety magazine's "10 Screenwriters to Watch" then had to deal with London and post-production for the third and final series of Luther, a programme that has screened in 162 countries and was credited with re-igniting the fuse of British drama and intrigue. Here, it has shown on UKTV while in Britain the two series regularly clocked up eight million viewers. Even the Americans got in on the act, falling for the maverick cop who can't see a corner without cutting it.
Played brilliantly by Idris Elba, who gained fame as drug kingpin Stringer Bell in cult favourite The Wire, the role of Detective Chief Inspector John Luther won both Cross and Elba Golden Globe and Emmy nominations.
And, in the case of the not-too-shabby Elba, legions of female fans.
Cross delights in telling the story of attending an Emmy after-party with his lead actor.
"Nicole Kidman's in one corner, Heidi Klum's in the other, everyone is far too A-list to check each other out but Idris walks in and every head turns. All night, whenever I look over, he is surrounded by women. There's just something about him."
Cross politely declines my request for details about the third series, or the feature film that six major studios are competing to make. Yet he's clearly delighted to be able to fly the Luther flag even higher.
"I absolutely love this character. The BBC asked me to create a new crime series and once I'd conceived the troubled, almost suicidal cop, he developed into this deeply interesting character. It's why I wrote the novel Luther: The Calling, which is prequel to the TV series. Even if I wasn't getting paid, I'd still be writing about Luther, because he's so compelling."
Cross landed the series on the back of Spooks, the BBC show about M15 agents in which he ended up bumping off most of the lead characters. It also likely brought him to the attention of the internet police: research had him poking around in the hornet's nest of dirty weapons, assassination techniques and deeply racist organisations.
"I'd be surprised if I wasn't on someone's list of people to watch, because at one stage there was all this vile content coming into my little suburban house. There are some utterly sick people out there."
Which begs the question: when you're trafficking in this much horror and violence, where do you go from here?
Dr Who, apparently. Last year Cross was invited to write two episodes of the cult sci-fi television series for its 50th anniversary. It was a life-long ambition and he relished the opportunity to write "old-fashioned scary episodes, the type I enjoyed when I was about 9 years old".
He was like an over-sugared toddler on set, and said meeting the current Doctor, Matt Smith, was a particular highlight. "He's my favourite Dr Who by far, although I also liked David Tennant."
I ask Cross about rumours he'll be writing an episode of Dr Who to be directed by Sir Peter Jackson and filmed in New Zealand. He drains his tea before answering.
"I couldn't possibly say but I've heard Peter Jackson may do it for the price of a Dalek! I guess you'll have to put it on your watch list."
He's less enthusiastic on the subject of Mama, his latest feature film directed by Mexican director Guillermo Del Toro, which has been called the biggest horror film for a decade.
Although it screened worldwide this year, New Zealand film distributors have shown no signs of a local release. "Scary Movie 5, which lampoons Mama, is in cinemas here but they haven't released the actual film, which drives me crazy."
I tell him friends who watched not-entirely-legal copies of Mama admitted they almost needed smelling salts. He laughs and tells the story of one of the fathers at his sons' school who downloaded an episode of Luther, seeing it even before Cross.
"He told me he didn't like the ending. Not only was he stealing from me, but he also didn't like what he'd stolen!"
It was one of those fortuitous twists of fate - which seem to happen regularly to Cross - that got him on Del Toro's radar. The director, in Wellington to make The Hobbit, had read one of Cross' books. He asked his people to track down the writer and was delighted to find Cross lived in the same city.
"We had lunch later that week and really hit it off. He said, 'Go home and write a script for Harrison Ford'" - which Cross did (something else he can't talk about).
Getting caught up in Del Toro's slipstream also involved fixing the script for the director's alien-attack film Pacific Rim, which also stars Elba, as well as writing Mama and Midnight Delivery, which charts the descent of a man who becomes a drug mule to save his son.
Much of the above was written deep in the creative cave of Del Toro's Los Angeles mansion, where actors such as Willem Dafoe would pop in to say hello.
But Cross' biggest Hollywood moment involved Ford, an actor he'd idolised since childhood. "When I was a kid, you were dead to me if you preferred Luke Skywalker to Han Solo. I love anything with Harrison Ford in it, from Star Wars to Indiana Jones. In fact, I wanted to do my thesis on Indiana Jones."
Turns out, Del Toro had orchestrated lunch with Ford in a deserted Santa Monica restaurant. "I was so nervous that morning I couldn't keep any food down. Meeting one's hero is so often a crushing disappointment, as I found out when I worked in publishing, but Harrison Ford was the exception - he was every bit as wonderful as I'd imagined."
So tense was Cross that in the limo on the way back to the hotel, when his wife rang to ask how the meeting had gone, he burst into tears. "I was so overwhelmed by the experience."
Cross leaps across 40 years to tell me the story of a small, lonely boy who found solace in Star Wars, one of the few bright spots in an otherwise grim childhood.
Born in Bristol, he moved to Edinburgh at age 6, when his mother ran away with a South African man, a character who even a writer as talented as Cross couldn't have dreamed up.
"Derek Cross was a white supremacist and an adulterer who began each morning beating the dog. He was a bishop in the Mormon Church and ended up absconding with the church funds. He also left my mother for another woman who, despite his racist views, was black."
The last time he saw him, in 1982, Derek had reappeared briefly to relieve his mother of her life savings. Yet, as he writes in his 2005 memoir, Heartland, Cross looks back on his step-father with great fondness.
"It was the first really formative relationship of my life and, in a lot of ways, Derek was the perfect parent. He gave me a love of books and he listened to me, which is a pretty powerful thing when you're a kid."
Despite being a bright child, school was a long and torturous experience, with bullies, insecurities and beatings. "I would throw up every morning before school."
He dropped out the same day he was kicked out of home, and spent the next few years developing a meaningful relationship with unemployment and petty crime. His turning point was a former girlfriend's parents, a "nice, middle-class couple" and the first people to take him seriously when he said he wanted to be a writer.
"They helped me through night school and then Leeds University, lending me money and being incredibly supportive. They came to my graduation, whereas my own parents didn't, and even though the relationship with their daughter ended, we still keep in touch."
He was thrown another lifeline with a sales job at a London publisher, where he helped to flog, among others, Bridget Jones's Diary. Those years, he says, were pivotal.
"Not only did I meet Nadya there, but I learned how the publishing industry works."
He'd been scribbling the whole time, folding the experiences of his lost years into his first novel, Mr In-Between, and then Always The Sun, which was long-listed for the Booker Prize in 2004. It wasn't the experience he was hoping for.
"I was out of publishing by then but I'd met enough authors to realise most of them are scum. Being nominated for the Booker opened a little box in me that I didn't like, because I started to feel as though this was my chance for revenge, to smite my enemies. I hated my reaction to the whole thing."
He and Nadya, whose name is tattooed on his inside left wrist, relocated to New Zealand in 2002, a country he fell in love with three days after arriving.
"Why wouldn't you live here? I feel a lot freer here than in [Britain] - no one cares who I am or what I do. I admire the Kiwi mentality; they're confident without a trace of arrogance and are accepting of all kinds of people. I'm the most English man ever, I spend my life embarrassed by what I've said or done."
It's one of the reasons Cross has resisted a move to LA. "I love that my sons are growing up with the Kiwi attitude."
He'd prefer not to travel - "London is better as an idea than a reality" - but says US television executives demand the writer be on set. Which is why he's trying to work out the logistics of spending four months in Costa Rica, where Crossbones is being filmed.
Asking him about future projects elicits an eye-roll: Cross has so many fingers in many pies. "Don't worry, I've got lots more ideas to keep you awake at night," he says, with a devilish smile.
