“We’re going for dinner.”

“Does ‘we’ involve Dermo again?”

Olivia is way too smart to let me yank her chain that easily. “His name’s Dermot, and yes, it does.”

I did impressed. “That’s four weekends running, am I right? Tell me something: is tonight the big night?”

Olivia called up the stairs, “Holly! Your father’s here!” While she had her back turned, I headed on past her into the hall. She was wearing Chanel No. 5, same as she has ever since we met.

Upstairs: “Daddy! I’m coming I’m coming I’m coming, I just have to…” and then a long intent stream of chatter, as Holly explained her complicated little head without caring whether anyone could hear her. I yelled, “You take your time, sweetheart!” on my way into the kitchen.

Olivia followed me. “Dermot will be here any minute,” she told me. I wasn’t clear on whether this was a threat or a plea.

I flipped open the fridge and had a look inside. “I don’t like the cut of that fella. He’s got no chin. I never trust a man with no chin.”

“Well, fortunately, your taste in men isn’t relevant here.”

“It is if you’re getting serious enough that he’ll be spending time around Holly. What’s his surname again?”

Once, back when we were heading for the split, Olivia slammed the fridge door on my head. I could tell she was thinking about doing it again. I stayed leaning over, to give her every opportunity, but she kept her cool. “Why do you want to know?”

“I’ll need to run him through the computer.” I pulled out a carton of orange juice and gave it a shake. “What’s this crap? When did you stop buying the good stuff?”

Olivia’s mouth-subtle nude lipstick-was starting to tighten. “You will not run Dermot through any computer, Frank.”

“Got no choice,” I told her cheerfully. “I have to make sure he’s not a kiddie-fiddler, haven’t I?”

“Sweet Lord, Frank! He is not-”

“Maybe not,” I acknowledged. “Probably not. But how can you be sure, Liv? Wouldn’t you rather be safe than sorry?” I uncapped the juice and took a swig.

“Holly!” Olivia called, louder. “Hurry up!”

“I can’t find my horse!” A bunch of thumps, overhead.

I told Olivia, “They target single mammies with lovely little kids. And it’s amazing how many of them don’t have chins. Have you never noticed that?”

“No, Frank, I haven’t. And I won’t have you using your job to i ntimidate-”

“Take a good look next time there’s a pedo on the telly. White van and no chin, I guarantee you. What does Dermo drive?”

“Holly! ”

I had another big gulp of juice, wiped off the spout with my sleeve and stuck the carton back in the fridge. “That tastes like cat’s piss. If I up the child support, will you buy decent juice?”

“If you tripled it,” Olivia said sweetly and coldly, glancing at her watch, “not that you could, it might just about cover one carton a week.” Kitty has claws, if you keep pulling her tail for long enough.

At this point Holly saved both of us from ourselves by shooting out of her room calling, “Daddydaddydaddy!” at the top of her lungs. I made it to the bottom of the stairs in time for her to take a flying leap at me like a little spinning firework, all gold cobweb hair and pink sparkly things, wrapping her legs round my waist and whacking me in the back with her schoolbag and a fuzzy pony called Clara that had seen better days. “Hello, spider monkey,” I said, kissing the top of her head. She was light as a fairy. “How was your week?”

“Very busy and I’m not a spider monkey,” she told me severely, nose to nose. “What’s a spider monkey?”

Holly is nine and the fine-boned, easy-bruised spit of her mother’s family-us Mackeys are sturdy and thick-skinned and thick-haired, built for hard work in Dublin weather-all except for her eyes. The first time I ever saw her she looked up at me with my own eyes, great wide bright-blue eyes that hit me like a Taser zap, and they still make my heart flip over every time. Olivia can scrape off my surname like an out-of-date address label, load up the fridge with juice I don’t like and invite Dermo the Pedo to fill my side of the bed, but there’s not a thing she can do about those eyes.

I told Holly, “It’s a magic fairy monkey that lives in an enchanted wood.” She gave me a look that was perfectly balanced between Wow and Nice try. “What has you so busy?”

She slid off me and landed on the floor with a thump. “Chloe and Sarah and me are going to have a band. I drew you a picture in school because we made up a dance and can I have white boots? And Sarah wrote a song and…” For a second there Olivia and I almost smiled at each other, across her head, before Olivia caught herself and checked her watch again.

In the drive we crossed paths with my friend Dermo, who-as I know for a fact, because I snagged his plate number the first time he and Olivia went out to dinner-is an impeccably law-abiding guy who has never even parked his Audi on a double yellow, and who can’t help looking like he lives life on the verge of a massive belch. “Evening,” he said, giving me an electrocuted nod. I think Dermo may be scared of me. “Holly.”

“What do you call him?” I asked Holly, when I had fastened her into her booster seat and Olivia, perfect as Grace Kelly, was kissing Dermo’s cheek in the doorway.

Holly rearranged Clara’s mane and shrugged. “Mum says to call him Uncle Dermot.”

“And do you?”

“No. Out loud I don’t call him anything. In my head I call him Squidface.” She checked in the rearview mirror, to see if I was going to give out about that. Her chin was all ready to turn stubborn.

I started to laugh. “Beautiful,” I told her. “That’s my girl,” and I did a handbrake turn to make Olivia and Squidface jump.

Since Olivia got sense and kicked me out, I live on the quays, in a massive apartment block built in the nineties by, apparently, David Lynch. The carpets are so deep that I’ve never heard a footstep, but even at four in the morning you can feel the hum of five hundred minds buzzing on every side of you: people dreaming, hoping, worrying, planning, thinking. I grew up in a tenement house, so you would think I’d be good with the factory-farm lifestyle, but this is different. I don’t know these people; I never even see these people. I have no idea how or when they get in and out of the place. For all I know they never leave, just stay barricaded in their apartments, thinking. Even in my sleep I’ve got one ear tuned to that buzz, ready to leap out of bed and defend my territory if I need to.

The decor in my personal corner of Twin Peaks is divorcé chic, by which I mean that, four years on, it still looks like the moving van hasn’t arrived yet. The exception is Holly’s room, which is loaded with every fluffy pastel object known to man. The day we went looking for furniture together, I had finally managed to wrestle one weekend a month out of Olivia, and I wanted to buy Holly everything on three floors of the shopping center. A part of me had believed I’d never see her again.

“What are we doing tomorrow?” she wanted to know, as we headed up the padded corridor. She was trailing Clara on the carpet by one leg. Last I’d looked, she would have screamed bloody murder at the thought of that horse touching the floor. Blink and you miss something.

“Remember that kite I got you? Finish all your homework tonight, and if it’s not raining I’ll bring you to the Phoenix Park and teach you to fly it.”

“Can Sarah come?”

“We’ll ring her mum after dinner.” Holly’s mates’ parents love me. Nothing feels more responsible than having a detective take your kid to the park.

“Dinner! Can we get pizza?”

“Sure,” I said. Olivia lives an additive-free, organic, high-fiber life; if I don’t do a little counterbalancing, the kid will grow up twice as healthy as all her mates and feel left out. “Why not?” and then I unlocked the door and got my first hint that Holly and I weren’t getting any pizza tonight.