Some people say that everything began with a Big Bang, but for me, that’s the last thing I really remember.
 
A bang so loud it made me forget everything else.
 
Everything except for a red balloon floating up into a clear blue sky.
 
And then darkness.
 
 
-
 
 
The insistent beeping of my alarm clock pulls me out of a super weird dream. Something about talking dolphins and the end of the world, I think.
 
It’s funny how that moment in a dream just before you wake up can seem like the most real moment there’s ever been. You completely believe that it’s true--that it’s really happening to you--even if you are talking to a dolphin at the time. But then when you open your eyes, the dream starts to fade right away, and all that you’re left with is a strange jumble of thoughts that don’t seem to make any sense at all.
 
Fumbling for the button on top of my alarm clock, I shake the last of the dream fragments from my mind, my eyes blinking in time with the numbers displayed on the digital screen.
 
 
9:00 a.m.
 
 
For a second I panic, wondering why nobody has tried to wake me up yet, but then I see the date.
 
 
SATURDAY, JUNE 9
 
 
It’s my birthday.
 
Jumping down from my cabin bed, I pull open the curtains, and sunlight floods into my room. Through the window I can see the gazebo that Mom and Dad have bought for my birthday party laid out across the lawn beneath protective plastic sheets, just waiting now for Dad to put it up. Over the back fence I can see the railway tracks, and beyond that the backs of the shops that lead up Cheswick Hill, the whole scene bathed in perfect summer sunshine.
 
I can’t stop myself from grinning. Today is going to be the best day ever. I’m ten years old.
 
The ancient Greek philosopher Pythagoras thought the number ten was the most important number in the world. He basically invented math using it and believed that the whole universe was built out of numbers. Pythagoras said that the number ten contained the key to understanding everything. If this is true, being ten years old is going to be pretty cool.
 
Maybe now that I’m ten, Mom and Dad will let me go to the shops on my own or even stay up late, just like Lily.
 
Lily’s my older sister. She’s fifteen and she hates me.
 
Mom and Dad say that Lily doesn’t hate me. They say she’s just a bit stressed at the moment because she’s studying for the PSAT, but I don’t think that’s a very good excuse. I passed my PSATs when I was seven and my SATs a year later, getting a distinction in physics, chemistry, and math. Now I’m studying for a bachelor of science in mathematics and physics.
 
The thing is, I’m “academically gifted.” Apparently this puts me in the top 2 percent of the population. That doesn’t mean I’m smarter than everybody else. I’m absolutely terrible at French. I just love learning about how the universe works. Lily thinks this makes me a freak.
 
Like I said, she hates me.
 
Pulling on my robe over my pajamas, I head down the stairs. The house is so quiet. Usually Dad’s already in the kitchen by now, noisily cooking up his Saturday-morning pancake breakfast while Mom sits at the kitchen table reading the newspaper.
 
I turn right at the bottom of the stairs, heading down the hallway and into the kitchen. Beneath my bare feet, the black-and-white tiles covering the floor feel freezing cold. I shiver. The kitchen table is deserted, the frying pan standing silent as the empty counters gleam. There’s nobody here.
 
I peer through the patio doors that lead out into the backyard, wondering for a second if Mom and Dad have sneaked out there to start putting up the gazebo for my party later today, but there’s nobody there either.
 
Maybe they are hiding somewhere and are going to jump out any minute singing “Happy Birthday.”
 
“Mom! Dad!” I call out. “Where are you?”
 
I stand still for a moment, ready to look all surprised when they suddenly appear. But nobody jumps out. The grin I’ve been wearing since I opened my bedroom curtains is slowly starting to fade. If Mom and Dad think this is funny, I’ve got news for them.
 
The living room is just as empty as the kitchen, the TV turned off and not a cushion out of place on the sofa. I’m not surprised that Lily’s not up yet, as she doesn’t usually surface until after ten on the weekend. This is because she’s a teenager and the hormones in her brain make her sleep late. Maybe that will start happening to me now that I’m ten. Now that I’m ten, everything might change.
 
I’ve done a loop of the downstairs now: hall, kitchen, living room, and back to the hall. If Mom and Dad are hiding somewhere ready to give me a birthday surprise, then they’re running out of rooms. Our house really isn’t that big.
 
Standing at the bottom of the stairs, I call out again.
 
“Mom! Dad! This isn’t funny. Where are you?”
 
Still no answer--just a creepy silence that seems to fill the house. I shiver, even though sunlight is streaming through the arch of tinted glass at the top of the front door behind me. Where is everyone? They wouldn’t have gone out without me. The excitement I felt when I sprang out of bed has now turned into a nagging sense of worry. I race up the stairs, two steps at a time, wanting this stupid game of hide-and-seek to be over already.
 
Heading around the landing, I push open the door to Mom and Dad’s bedroom.
 
The room is still in darkness, the curtains drawn against the morning sun, but in the light spilling in from the landing I can see that nobody’s here. The bedspread is pulled neatly across Mom and Dad’s king-size bed. It doesn’t look like it’s even been slept in.
 
The twisting worry that’s been coiling inside my stomach is now tightening into a tense knot of fear.
 
Doubling back along the landing, I glance back inside my bedroom and then peer around the bathroom door too, just to double-check. But both rooms are empty. The only living thing I can see is a spider scurrying toward the faucets when I pull the shower curtain back.
 
I shiver again, the sunlight streaming through the bathroom window seeming to lack any kind of warmth. Something’s not right.
 
Back on the landing, I glance toward the second flight of stairs that lead up to Lily’s room in the attic. A no entry sign is stuck to the wall at the bottom of the stairs, and beneath this Lily has written NO SISTERS ALLOWED.
 
She means me.
 
I wouldn’t normally dare to go anywhere near Lily’s room on a Saturday morning. Her rage can be positively volcanic if her weekend sleep is disturbed. But this isn’t a normal Saturday. It’s my birthday, and I want to know where everyone is.
 
“Lily!” I shout up the stairs, my words echoing off the empty walls. “Are you up yet?”
 
There’s no answer.
 
“Lily?”
 
More silence.
 
I glance at the no entry sign and then shake my head. This is an emergency.