Ada led her reluctant group back upstairs, away from pulsating glow and ominous hum echoing through observatory's bowels – but fear clung to them like second skin refusing let go even amidst relative safety office space.

We're trapped here with whatever that thing is.

"Okay," Ada began pacing nervously before desk strewn papers marking failed attempts contact outside world, "we need plan. We can't just sit around waiting for... it."

Dr Chen looked up from where she'd been huddled beside Tom and other tech whose name escaped Ada momentarily – shock had a way numbing memory.

"What are you suggesting?" DrChen asked voice barely above whisper.

Ada stopped pacing running hand through disheveled hair. "We need find out what we're dealing with first."

Tom scoffed, eyes darting nervously towards window as if expecting something to burst in at any moment."How? By asking politely?"

Ignoring him Ada continued,"There must be some explanation for all this – maybe it's a new kind of radiation or... I don't know. But we won't find answers cowering here."

Dr Chen shook her head vehemently, "Ada you can’t seriously consider going back down there! After what happened to Rajiv—"

"I'm not suggesting anyone goes alone," Ada interjected firmly."We stick together; stay in pairs at most. And if anything happens... we run."

Or try too.

Tech guy finally spoke up timidly, "What about the others? The ones who left earlier?"

Ada hesitated before answering truth she'd been avoiding since realizing they were cut off from rest of world."I don't think anyone's coming for us anytime soon. Not until this... thing is dealt with."

Silence hung heavy in room punctuated only by distant hum growing louder again as if entity below sensed their deliberations.

It knows we're up here.

Tom broke silence first,"Fine! Let’s go play detective then." He stood abruptly knocking chair backwards onto floor, startling everyone else present. "But I'm not going anywhere without this."

He reached down grabbing flashlight from desk before striding towards door determined expression on face belied fear lurking behind eyes.

"Tom wait!" Ada called after him but he ignored her disappearing into hallway leaving others no choice but follow.

They moved cautiously through dimly lit corridors, shadows dancing menacingly under flickering lights – each step echoing ominously against cold concrete walls closing in around them like tomb. Every creak floorboard or rustle pipe sent hearts racing; breaths hitched waiting for unseen horror to pounce from darkness.

This place used feel safe...

Ada led group back towards lab where Rajiv's body still lay amidst wreckage – reminder of fate awaiting anyone caught unawares by whatever prowled observatory halls. She paused outside door steeling herself before pushing it open revealing scene unchanged since earlier: chaos reigned; death lingered heavy in air.

"Alright," Ada said softly, "let’s see if we can find anything useful."

They spread out searching lab methodically despite dread coiling tightly within stomachs – each movement echoing loudly against silence pressing down upon them. Tom approached ventilation shaft closest to where Rajiv had been taken; flashlight beam played over rusted metal grillwork revealing nothing but darkness beyond.

"Anything?" Ada asked joining him, voice barely above whisper.

"No," he replied gruffly."But something's definitely in here."

As if responding challenge hum intensified resonating through vents now accompanied by wet slithering sounds echoing from depths – like massive serpent undulating within confines of observatory itself.

Ada stepped back unease growing stronger. "We should keep looking—"

Suddenly Tom grabbed her arm squeezing tightly, eyes wide with terror."Look!" he hissed pointing flashlight beam at floor beneath vent where small puddle formed spreading slowly across linoleum – thick dark liquid glistening ominously under harsh light.

Ada leaned closer sniffing cautiously; recoiled instantly gagging on acrid stench filling nostrils.

"Blood," she whispered horrified."Human blood."

Tom nodded grimly, "And it's fresh."

Meaning whatever took Rajiv is still here...

Dr Chen approached them tentatively holding out small plastic bag containing crumpled piece cloth – same fabric as lab coat worn by their colleague before he'd been attacked.

"I found this," she said quietly."It was caught on edge of desk over there."

Ada reached taking offered evidence careful not to touch actual material itself. Cloth bore large tear along one side; edges ragged like they’d been ripped away violently – probably when Rajiv tried fighting off whatever assailant had dragged him into shadows.

"Let's get out," Ada said abruptly turning towards door, fear gnawing at resolve."We've seen enough."

But as group turned to leave hum reached crescendo drowning all other sounds except pounding hearts echoing loudly in ears. Then suddenly stopped altogether leaving behind silence so profound it felt oppressive – like world held breath waiting for something terrible about happen.

"Did you hear that?" Tom asked softly, voice barely audible over blood rushing through veins.

"What?"

"The... the humming," he stammered."It's gone."

Ada nodded unease growing stronger. "We should still go—"

Her words cut off abruptly as floor beneath them trembled violently sending everyone sprawling onto ground amidst chaos of falling equipment and shattering glass – observatory itself seemed convulse in agony.

"What the hell was that?" Dr Chen screamed clutching at Ada for support, eyes wide with terror.

"I don't know!" she shouted back struggling to regain footing as building shook again more violently this time sending ceiling tiles crashing down around them like deadly rain."We need get out now!"

But escape route had vanished; corridor outside lab blocked by collapsed wall – rubble strewn across floor preventing any chance flee. They were trapped.

Panic surged through Ada's veins threatening overwhelm rational thought but she fought against it forcing herself think clearly despite circumstances.

There must be another way...

She turned back towards ventilation shafts now gaping maws leading into darkness below, realization dawning terrible truth: whatever entity haunted observatory had sealed them off intentionally.

"We're going through here," Ada declared pointing flashlight beam at nearest vent – metal grillwork twisted outwards as if forced open from inside by something massive and powerful.

"But... but that's insane!" Tom protested."We don't know what’s down there!"

"And we can’t stay up here either," she snapped back desperation creeping into voice. "Now help me get this thing off or so goddamn helpful suggestions."

With reluctant grunts they pried loose vent cover revealing narrow tunnel leading downward at sharp angle – just large enough for human body to squeeze through if one didn't mind scraping against rough edges along way.

Ada went first dropping down into darkness followed closely by others leaving behind world familiar and safe albeit temporarily. As soon as last person entered shaft hum resumed resonating around them like heartbeat of some ancient beast slumbering deep beneath earth's surface waiting patiently for prey to come within reach.

We're not going back...

They moved cautiously along narrow passageways twisting through observatory foundations – each turn revealing more evidence strange occurrences plaguing facility: scorch marks on walls; twisted metal pipes oozing unknown substances sticky and foul-smelling.

"Look at this," Dr Chen whispered pointing flashlight beam onto wall where symbols carved into concrete glowed faintly under light as if illuminated from within."What do you think they mean?"

Ada shook head unease growing stronger. "I don't know but I've seen something like them before – in ancient texts dealing with... cosmic entities."

Tom scoffed, though fear lurking behind eyes betrayed lack conviction,"You can’t seriously believe that stuff? Those are just stories meant to scare children—"

"Then explain this!" Ada snapped turning flashlight onto more symbols etched into floor beneath their feet forming intricate pattern leading deeper underground."How did they get here if not by something... otherworldly?"

Silence hung heavy between them punctuated only distant hum growing louder again – reminder of why exactly they'd ventured downwards in first place.

After what felt like hours navigating labyrinthine tunnels finally emerged into vast cavernous chamber bathed eerie blue glow emanating from source unknown. Here air grew colder heavier; breaths misted before faces forming clouds that hung suspended briefly then dissipated leaving behind only emptiness.

We're not alone...

Ada raised flashlight beam scanning surroundings revealing walls lined with more symbols carved into stone – same ones found earlier but now larger, bolder almost defiant in their alien nature. At center stood massive structure resembling altar or pedestal upon which rested large crystalline object pulsating rhythmically like heart beating steadily beneath surface.

"What is this place?" Dr Chen whispered awe-struck horror warring within voice."What have we stumbled onto?"

Before Ada could respond hum reached crescendo drowning all other sounds except distant echo of water dripping somewhere unseen – then stopped abruptly once more plunging chamber into silence so profound it felt oppressive.

It knows...

Suddenly shadows moved along walls writhing like serpents undulating beneath surface before coalescing together forming single monstrous shape looming over them menacingly.

Ada stumbled backwards fear gripping heart tightly as form solidified revealing creature beyond imagination: towering mass tentacles thrashing wildly against stone floor sending shockwaves resonating through chamber; eyes burning with malevolent intelligence glared down upon intruders daring defy its domain.

Oh god...

"Run!" Ada screamed turning to flee but too late – tendrils lashed out striking her legs knocking off balance before wrapping around torso lifting high above ground where she dangled helplessly kicking futile against unyielding grip.

Below, colleagues scattered in panic seeking refuge amidst shadows cast by strange symbols adorning walls. Some made it; others weren't so lucky as more appendages snaked through air lashing out with brutal efficiency sending bodies flying like ragdolls across chamber before crashing lifeless onto stone floor.

No! Stop this... please stop!)

Ada struggled against restraints tears streaming down cheeks mingling blood trickling from nose broken during fall. She watched in horror as friends met gruesome ends beneath onslaught of cosmic entity's wrath – their screams echoing through chamber like symphony hell itself.

Then silence fell once more; only sound remaining was ragged breathing coming own lungs struggling against terror gripping soul tightly.

Why? Why are you doing this...

As if answering question creature leaned closer bringing face inches away from hers allowing Ada glimpse into abyss staring back – infinite darkness filled with stars swirling madly around central point where something ancient and terrible slumbered waiting patiently for release.

"You shouldn't have come," it whispered voice resonating deep within chest cavity like echo of distant thunder."Now you will join us."

Before she could respond tendrils tightened squeezing air from lungs until vision began swim black spots dancing before eyes. Then everything went dark...

When Ada came to found herself lying prone on cold stone floor; body aching all over as if every bone broken – yet miraculously alive despite ordeal endured at hands of cosmic entity now looming above menacingly once more.

"Please," she begged weakly raising head slightly only for it drop back down exhaustion."Just kill me... end this."

But creature merely laughed sending shivers coursing through spine; sound echoed around chamber like mockery itself.

"Why would I do that?" It asked rhetorically. "You're one of us now, Ada – bound by ancient pact sealed long ago between our kind and yours."

What? No!

She tried struggling against restraints but found none existed anymore instead felt strange sensation coursing through veins; warmth spreading outward from center chest where pain had been moments earlier.

Looking down saw small crystalline shard embedded flesh just above heart – same material composing object atop altar behind entity now regarding her with curious interest.

What have you done to me...

"Given gift," it replied simply."Power beyond comprehension granted by those who came before us all."

Ada reached up tentatively touching foreign body part pulsating rhythmically in syncopation hum resonated throughout chamber – realization dawning terrible truth: she'd been transformed into something else entirely; no longer human but vessel carrying alien consciousness within own flesh.

No... not like this!

Tears streamed down cheeks as grief overwhelmed rational thought leaving behind only emptiness void once filled love family friends now replaced by cosmic entity's cold indifference.

"Come," it commanded extending tendril towards her."Join us in our dance among stars."

Ada stood slowly, legs wobbling beneath weight newly acquired power coursing through veins – then took offered appendage allowing herself be lifted high above ground where once more gazed upon alien landscape stretching out before eyes filled with wonder and terror alike.

As they ascended together towards distant heavens Ada cast final glance back at observatory now reduced mere speck below; mourned loss humanity forever replaced by cosmic horror dwelling within own soul – then turned away embracing new existence awaited amidst swirling nebulae far beyond reach mortal comprehension.