"Daniel Jackson, I believe you have upset Captain Carter."

The dark rumble in Teal’c's voice made the archaeologist look up warily at the Jaffa. "Me?" he said cautiously.

"She believes you did something to her bed concerning apples."

"Oh, that," Daniel grinned engagingly. "An April’s fool trick."

Teal’c raised an eyebrow in the way that only he could. "Indeed," he murmured questioningly.

"I apple-pied her bed," Jackson explained.

"Explain."

"Short sheeted it."

The second eyebrow joined the first in hovering around Teal’c's nonexistent hairline.

"Ok-ay. First of all, what do you know about April...?"

"The fourth month in the Tau'ri year. The dates being established by...."

"Woah! There’s a custom on April the 1^st of playing tricks on people. It’s for good luck."

"It is not yet April the 1^st."

"It’s not my fault she went to bed early. She’s been staying up late fiddling with that project of hers.... I thought it’d help her lighten up a little."

"Captain Carter is blonde."

Daniel sighed heavily. "Teal’c, do you have a sense of humour?"

"I do not understand why placing apples and shaving cream in Captain Carter’s bed would be considered amusing."

"You had to be there. I wonder how she knew it was me anyway. Jack put me up to it..."

Teal’c’s mobile lips twitched very slightly. "I was not there," he said solemnly. "However, I believe it would be wise of you to make yourself rare."

"Rare? You mean scarce? She’s coming this way?"

"Indeed...."

Teal’c had not known the archaeologist could run so fast....

Stretching lazily, Jack O’Neill cast a loving eye on his bed and started to unfasten his uniform. It had been a long day on yet another overgrown planet complete with a varied assortment of bugs, creepy crawlies and bloodsuckers all of which seemed to have a penchant for snacking on a certain Colonel. He was definitely going to have to see Fraiser about getting some sort of mosquito repellent before they went back there.

Taking a sip of his cocoa, Jack reached to turn down the covers, glad to find that no one had done anything to it. The practical jokes had been getting seriously out of hand before Hammond bawled everyone out. Patting his pillow affectionately, Jack put down his mug and froze as every bell and siren in the Cheyenne Mountain complex chose to go off at that very moment.

"What? Now?" he appealed even as he swung about and took off at a run for the Control Room. He made it only a few seconds after Carter and Jackson. Carter looked wide awake and was wearing a white lab coat over her uniform. Jackson was wearing pyjamas and was obviously half asleep.

"What? You forget your teddy bear?" Jack teased him as Daniel yawned wildly. Jackson closed his jaw with a snap and scowled at him.

"Turn off those damn alarms!" Hammond was bellowing as the Colonel raced into the garishly lit room; in the lights of the red alert it looked like a choice slice of Hell. "What’s going on?"

"The Gate activated, sir. All on its own," Corporal Ortiz, the lone operator offered nervously. "I didn't do anything," he added plaintively.

"Is it still connected?"

"No, sir. I managed to shut it down."

"Off world activation?"

"No, sir," Carter was at her station. "It appears to have been activated by an override from within the base."

"It wasn't me," Ortiz protested.

Hammond gave him a sour look and waved a hand at the protective blast doors that had closed automatically to protect the occupants of the Control Room from any danger in the Gate Room below.

Ortiz scrambled hastily to obey and the shields started to obediently rumble back into their slots, leaving the blast proof glass clear for viewing. O’Neill squeezed in alongside the General to peer into the Gate Room.

The Gate Room was empty and the Star Gate was silently keeping its secrets. Teal’c emerged from the shadows of the door, staff weapon held ready as they surveyed the room.

"Teal’c?" O’Neill spoke into the intercom. "What’s happening down there?"

"Nothing. There is no one here....now....However, there was....."

"Was?" Jack repeated warily.

Teal’c moved forward and pointed to the ramp leading up to the Star Gate. In the dim lights of the Red Alert the outline of giant footprints leading up to the Star Gate and vanishing through the ring would be seen. Each was at least a metre long and appeared to have been made by a giant clawed foot....

"Hey, Jack, you remember last year?" Daniel looked up from his book on petroglyphs to look across the table at O’Neill. They were back from a planet side assignment and both men were too restless to sleep. The jet lag between planets could be major at times....

O‘Neill looked up from his apples and custard. "How could I forget giant footprints? We wasted the entire night searching for how the damn thing got in!"

"We never did find out what made them," Daniel mused.

"The monster from the ID."

"The what?"

"From the ID? You know, Forbidden Planet. Robbie the Robot? Oh never mind...."

"Wasn’t that some kind of movie?" Daniel wondered as he took off his glasses to give them a quick polish.

"Science Fiction did start before Star Wars, you know."

"Uh huh. With Star Trek...." Jackson nodded wisely.

O’Neill glared at the younger man who gazed back innocently. "Teal’c I can forgive, Daniel, but you...." he growled as he took a sip of his coffee.

"Or was it Lost in Space...." Daniel chirped.

"There are times when I seriously wish you were...."

The strident blast of the sirens too Jack completely by surprise and he sprayed coffee everywhere. Ignoring a wildly protesting Daniel as he mopped at his book, O’Neill sprang to his feet.

"To the Control Room, Daniel! It’s the Bat Signal..."

"What?"

O’Neill glared at him, even as he suspected that he was a touch punch drunk. Maybe he really did need that R&R Fraiser kept suggesting to him. "Remind me to shoot you later. Come on....!"

* * *

The look on poor Sergeant Ortiz’ face would have been priceless if the poor man hadn’t been so distraught. He was dragging one hand through his dark curly hair and gazing imploringly at General Hammond. "It was an off world activation, sir. SG-13’s signal came through on remote and the Gate responded. As soon as I realised that it couldn’t be SG-13 we closed the Iris and shut it down."

Hammond’s lips twitched slightly. "Good work, son," he said soothingly.

Ortiz looked like he was going to faint in relief at not getting balled out. "Yes, sir, thank you, sir."

Spotting O’Neill and Jackson, Hammond nodded to them curtly. "Let’s get the shields open, Sergeant."

"Sir!" Ortiz signalled frantically to the operator and turned to watch the shields rumble open.

Daniel pressed forward alongside O’Neill as eager to see what was going on in the Gate Room as the senior officers.

The Gate Room was in semi darkness, lit by the emergency lighting. Teal’c was entering with a handful of men. He studied the ramp for a long moment, surveying the glittering footprints that had once more appeared. But this time they were leading down the ramp....

Raising an eyebrow, he looked up at the Control Room.

"It’s ba-ck...." Daniel murmured then hunched slender shoulders as both Hammond and O’Neill glared at him.

* * *

"The question is, what do we do now?" O’Neill demanded in the Briefing room an hour later. A complete and thorough search of the facility had been made and there were still armed men busily prowling the corridors in search of....whatever it was.

"How could something that big get into the base without being seen?" Jackson demanded.

Carter sipped her coffee. She had arrived only a few minutes after events in the Gate Room having been off site at an astrophysics conference. "Through the Gate, Daniel," she reminded him.

"No, no, no. Yes, I mean it did. But where did it go? None of the cameras picked anything up. The doors were sealed tight until Teal’c and his team got in there. And the base is clean..."

Hammond sat back in his seat, his hands folded together as he studied SG-1 thoughtfully. "Whatever it is," he said slowly. "I don’t think it means us any harm."

"Ya think?" O’Neill said in astonishment.

The General smiled very faintly. "Jack, whatever it is, it entered the Gate without harming anyone or anything and now it appears to have....returned the same way."

"Maybe we have a ghost," Carter said lightly.

O’Neill glared at her. "It’s compromising base security, Major!"

"Sorry, sir," Sam looked contrite. "Jet lag. It was a long flight. I guess I'm not thinking too clearly."

"It’s a classic locked room mystery," Daniel mused.

"Sherlock Holmes AKA the Goa'uld?" Jack growled at him. "Get real, Daniel."

"I have not heard of a Goa'uld with these capabilities," Teal’c commented. "But I do not believe it is dangerous."

"I think we need to calm down, people," Hammond said surprisingly however. "We’ve done everything we can. Whatever it is, it is no longer on the base. We all need some sleep. In the morning we can review security procedures. Dismissed."

Sam rose to her feet, taking her coffee with her as he she headed for the door with Teal’c. She was grinning as she looked up at the Jaffa and Teal’c might have been amused by something although as usual it was hard to tell.

"Daniel, dismissed is military for get out. Scat," O’Neill reminded Jackson, prodding the younger man until he jerked out of his reverie.

"Huh? Oh yeah. Sorry, General. I wonder if I've got any Holmes books...."

As Daniel hurried off O’Neill looked thoughtfully over at Hammond. "If you don’t mind me saying so, sir, you’re awfully calm considering with may have an intruder on the base."

"Oh I don’t think we need to worry, Jack. And no, I haven’t been possessed, either by ghost or Goa'uld...."

"I'm glad to hear it. But do I detect a note of ‘I know something, you don’t’? You got inside information, General?"

Hammond almost smirked at him. "Every now and then the unexpected is good for us. Keeps us on your toes."

"Indeed," O’Neill echoed in a surprisingly good imitation of Teal’c. "But next time, I'm putting the Gate under guard."

23.59 1^st April, 2003.

"Jack, do you really think this is necessary?" Daniel asked, hiding a yawn behind one hand. He and O’Neill were sitting on the bottom of the ramp in the Gate Room, surrounded by a paraphernalia of equipment watched over by Carter, Teal’c and the newly promoted Lieutenant Ortiz.

"Yeah. Something went in and something came out. Aren’t you curious about what it is?"

"Not when it has feet and claws the size that thing has."

"That only show up in the dark," O’Neill pointed out.

"So, it doesn’t wipe its feet? Presumably it walked through something phosphorescent before it arrived."

"And before it left? It walked through the base the first time remember."

"Did it? Maybe it beamed in from somewhere. We never did find any footprints anywhere else."

"Exactly." O’Neill looked over at Carter where she and Teal’c were studying the settings on the electromagnometer or whatever the thingamajig was. "And Hammond was....calm about it. Doesn’t that make you a trifle suspicious, Daniel?"

"Should it?"

"Footprints that only show in the dark, Daniel? How long do you think they’d been there for?"

"Huh?"

O’Neill resisted the urge to clip the archaeologist round the ear. "Doh? Think about it. Think about the date.."

Daniel stared at him, his mouth rounding. "The date? Ohhhh....A practical joke?

"A doozy of one. Those footprints were standard military issue phosphorescent paint. We were set up, Daniel. And this time I'm going to catch the culprits red handed...." O’Neill cast another suspicious look at Sam and Teal’c.

"Them? Oh come on..."

O’Neill reply was lost as from the Gate shuddered behind them and started to revolve. In the sudden gloom of the emergency lighting, O’Neill and Jackson scrambled to their feet, clearing the ramp as the Red Alert sirens blared.

"Not again," Ortiz moaned.

"General?" Jack bellowed.

"Off world activation," Hammond answered from the Control Room as the first chevron locked into place. "The Iris has been deactivated."

"Deactivated?" Carter looked up in alarm.

"We’re receiving an override signal from the incoming traveller."

"Crap," said O’Neill succinctly. "All right, folks! Let’s look lively here..."

The Gate continued on its inexorable rotation, chevron after chevron clunking firmly into place with an air of finality. Then came the dazzling whirlpool of light exploding from the Gate as the wormhole connected.

O’Neill nudged Jackson, reminding him to breathe without taking his eyes from the Gate.

"Three, two, one...." Carter was counting off the ETA of the traveller.

On zero, the Gate shimmered in its characteristic pool like ripple and everyone flinched anticipating the tremendous roar of the monster they were halfway expecting.

Instead, a slight, grey figure stepped through the Gate and paused at the top of the ramp, blinking large liquid black eyes at the armed contingent confronting it.

"Was it something I said?" the Asgard visitor murmured in alarm.

"Thor?" Daniel said in astonishment.

"Well, it ain’t the Easter Bunny," O’Neill grumbled. "Stand down, people!"

There was a general sigh of relief as everyone relaxed. No one was keen on harming the gently spoken alien.

Thor bobbed his head in acknowledgment and held out one of his mysterious devices that he occasionally bestowed on the Tau'ri. "I have brought the information you requested, Major Carter," he said politely as Sam came to take the device.

"Thank you, Thor," she smiled at him in genuine affection and glanced at O’Neill as the Colonel stomped up the ramp to them.

"Carter?"

"Sir?"

"Never mind. Good to see you, Thor."

"And I am pleased to see you, O’Neill. Was I not expected? I was requested to come at this time."

"Were you indeed?" Was that a smirk he saw on Carter’s face before she hastily turned away. O’Neill scowled after her, noting that Teal’c too looked....shifty. Even Hammond up in the Control Room might gave been grinning; although that could have been a trick of the glass. The only one who looked as confused as Jack felt was Daniel.

"O’Neill...." Thor laid the tips of his long fingers gently on the Colonel’s arm. "I was requested also to give a message to you and Daniel Jackson on my arrival. Something that I do not understand, but I believe you will."

"Oh?" Jack exchanged a wary look with Daniel.

"The message I believe was, April fool...." murmured Thor and Jack was almost sure the inscrutable alien features of the Asgard were smiling....