"Off you go, and stay out of trouble ?"

"Yes, Mum."

"Yes, Ma."

"Yes, Aunty Joan."

"Huh..."

"Josie ?"

"Yes, Mrs. Jones."

A nice, late-Spring afternoon mountain-biking quiet 'New Forest' trails was a really cool way to chill after a long, hard week at college. Sue, my busty, bossy, blonde half-sister led, of course, of course. The oldest of us by three years, she was going to Uni in the Autumn. Medieval History with a 'side' of Archaeology, no less ! We reckoned she'd do a conversion course to CSI when the fun wore off.

Her slight cousin Jackie was, like me, small, dark-haired, almost Pictish. We were often mistaken for sibs, could pass as twins, would cheerfully 'double up' at Halloween. Best friends since pre-school, we were allied against the world. Yes, I fancied her, and I knew she thought I was 'cute'. Sadly, Jackie had a long-standing crush on Josie, who was a sassy red-head with the 'gift of the gab' and an unconcealed loathing for males. Gossip held she'd been abused by a ghastly 'uncle', but we didn't dare ask. Fortunately, Josie tolerated me. Solidly 'Science Stream', I did 'Gymnastic Dance' with Jackie and held a Judo Blue. Despite Josie's oft-cruel jibes, I was unfailingly polite. Better, I treated her as a 'Person' rather than a 'Pretty Dolly'. To her mind, if I wasn't a testosterone fuelled lout with groping hands, I must be 'Gay'. She was so wrong, but it let us get along.

So, there we were, a young adult and three mid-teens, cheerfully pedalling those pretty paths. Though a trope, of the four of us, only I could navigate reliably. Even misandrist Josie had to admit my quiet competence with map, compass and GPS.

Then everything changed.

First, my Garmin froze. A basic model, it was tough as an old boot, had no problem holding a multi-satellite 'lock' through thick foliage. To my surprise, all the 'bars' dropped away.

"Huh ?" I braked to a halt, peered at the compact display. No bars ? None ? Hastily, I pressed the Garmin's function button to tag our current position. Cell phone coverage here was 'sparse' so, if you needed help, a map reference could save a lot of time.

The others were ten seconds ahead before they realised I'd stopped. They slowed, pulled off the path, looked back. Sue called, "Jack ? What's wrong ?"

"GPS is off. Would you check your phones ?"

The three exchanged puzzled looks, then decided to humor me. They hauled out their smartphones while I woke my tiny, 'hand-me-down' clamshell.

"No signal ?"

"No bars ?"

"No network ?"

"Me, neither." I hesitated, said, "This old thing should have found a neighbouring cell, so that's three different networks and several masts shot. I-- I think we should go back."

Sue took a long, deep breath, asked, "What do you reckon ?"

"I don't know." I shrugged. "Nothing fits. Damage to a cell mast or masts wouldn't hurt the Garmin. A big solar flare might kill the GPS, but our phones should be okay. An 'EMP' would fry my Garmin and your 'live' phones."

"Uh..." Sue thought it through. "Sorry, guys. Jack's right. Something bad's gone down. We go back."

Josie grumbled loudest and longest but, with her iPhone unaccountably off-line, she couldn't check the news, never mind Twitter.

"We should head for the road," I offered. "A mile or so to the left, there's that little tea-shop--"

"Drinks, loos, news." Sue nodded. "Okay, Jack, set a course."

I fetched out map and compass, checked the GPS reference I'd stored was plausible, checked the sun-angle. "That-away."

Half-way to the road, we met a couple of puzzled joggers at a trail junction. They waved us to a halt. West-Coast US by his accent, the man called, "Hey, kids ! Are your GPS and phones down ?"

"Yes, Mister," I replied. "Garmin's no bars and three networks are off."

"Eff !" He shook his head. "Well, that blows our geo-cacheing run..."

"Have you map and compass ?" I asked, seeing neither.

"Huh ? For a quaint 'Country Park' ?"

"This is the 'New Forest'," I stated. " 'Re-Wilded' a thousand years ago. Now, there's lots of shallow mining pits and foundations to turn ankles, break legs. The Wild Boar are a 'Force of Nature'. Sows with piglets may attack on sight. Even with 'bivvy' gear, it can be unsafe after dark. And isn't tonight a 'New Moon' ?"

"You cannot be serious !"

"Jack's called it right," Sue warned. "We're heading for the road..."

"Three miles that way." I waved my compass. "Then left about a mile to a tea-shop."

"Wash-room, food, drink, shelter, perhaps news ?" Sue offered.

"Huh ?"

"No GPS ? No cell-phones ? Something bad's gone down..."

"Ah..."

"See the Sun ?" I pointed to the South-West. "Even with 'four minutes per degree', you can use that as your compass for the next hour or so. Just hold that angle, veer slightly left if in doubt."

"Thanks, kid."

"You're welcome. Go careful." As we pedalled out of sight, my glance back found them turning to follow us.

About five minutes later, Josie sat up in her saddle, exclaimed, "Yuck ! What's that smell ?"

"Uh, which one ?" Sue asked, sniffing warily.

"Hospital ? Dentist ?"

Before Sue could reply, we reached a fork in the path. Oddly, both ways seemed foggy. Sue hesitated, asked, "Which way, Jack ?"

"Huh ?" My oil-damped compass was swinging through fifteen or twenty degrees, gave no clue. I glanced over my shoulder, found the rising mist or fog was rapidly obscuring the Sun. "Left, but-- Huh ? Now my compass is spinning !"

"No way !"

"Look !" I held it steady and level, as far from my bike's frame as I could. Despite the oil fill, the needle was surely turning clockwise faster than a second hand's sweep. As we watched, it turned a full circle.

"Weird..." Jackie allowed as it started around for the second time. "What could do that ?"

"Uh..." I racked my brains. "Geo-magnetic sub-storm, perhaps ? A really big one ?"

"Aurora stuff ?" Sue asked.

"Uh-huh... But I'd expect the compass to swing left and right, not go round and round..."

"And round," Jackie warned. "It's getting faster..."

"Perhaps there's still iron ore under here ?" I waved. "That might--"

"Hey !" Josie grumbled. "Now my teeth hurt !"

"And mine !" Sue put a hand to her jaw.

"What's that humming ?" Jackie puzzled.

"Uh ?" I blinked. "Quick ! Turn your phones off !"

"Huh ?"

"Turn your phones off !"

"What ?"

"Turn your phones off and step away from the bikes !"

"Jack ?"

"It may be a 'Carrington Event' !" I scrambled from my bike, shut off the Garmin. "1859 ! Biggest solar storm in centuries ! Smaller one in, um, 1989 knocked out power to Quebec !"

"Uh !" Josie moaned, dropping to her knees beside her bike. "My teeth HURT !"

"Aaah !" Sue howled as Jackie clutched her head in silent agony.

Now I could hear it. The hum rose to a whine, to a shriek--