Synopsis
The opening page has 5 undisclosed people stealing deadly viruses from the United States Army Medical Research Institute of Infectious Diseases lab. (The comic says it's a secret location but Wikipedia reveals it's at Fort Detrick in Maryland.)
Later the Avengers are called in and arrive by Wakandan flying craft Bubastis. The invaders and their loot can't be found. The staff and guards and their families are quarantined at the site, and panic is building. Leaving Ghost Rider in charge of the plane Black Panther, Captain Marvel, Iron Man and She-Hulk drop down to the scene. Iron Man relies on his armour but the other 3 wear breathing masks.
Inside they find the place and occupants splattered with blood. A leaking vial has affected some guards who turn violent. Angry She-Hulk rips her mask off and gets infected too. She picks up a fridge full of vials and throws it through a wall because she says she can hear friends on the other side. In the next room they see Angela, Spectrum, Spider-Woman, Wiccan and Winter Soldier, most of of whom are ex-Avengers.
The Avengers take them in custody to Avengers Mountain HQ claiming innocence and ignorance. Security camera and forensic evidence indicate that these heroes really did commit the crime. Captain America joins BP, CM and IM in trying to figure out why. These aren't Skrull imposters and there's no trace mind-control. But they've also suffered no effects from released viruses as She-Hulk and the guards did, which Tony Stark can't explain. Panther has called in Blade who has said they should leave *him* to deal with the situation.
The suspects are sharing a cell and discussing what's going on. They don't remember how they got there, and some of them are strangers to each other. They're hungry but Wiccan says his magic is not to be used for trivial things like conjuring up pizza. There seems to be some missing dialogue about a scientific explanation because Angela dismisses science, and then Blade appears in the room, rips out the surveillance cameras, and says science has nothing to do with it. He says he knows what happened to them but didn't want to explain it to the other Avengers.
He tells them about an incident in Berlin many years ago (and he's shown in his costume from the Tomb Of Dracula days) where he ran across 3 vampires attacking a young woman. He killed 2 of the vamps but then the 'victim' tore apart the 3rd. Blade then killed *her* and she shape-shifted into something else. Eric Brooks then found the real girl alive in a nearby dumpster and she was the Chancellor's daughter who didn't remember what had happened to her. But the important part is that he got a feeling that *something* had taken note of him and was whispering in his head. And he got the exact same sensation when he saw the suspects here.
He also adds that he took a sample of the thing and got Tony Stark and T'Challa to build him a detector for such things. (Which doesn't really fit with the Tomb Of Dracula timeframe.)
Now he teleports them to a temple in the Indonesian rainforest (using the borrowed teleportation device which got him into their cell) because his detector tells him that's where the real villains are. He also explains that he didn't involve the Avengers because he didn't want to risk what was messing with *his* head getting into *theirs*.
Wiccan recognises the Temple Of Three as the place where Dr Strange and Dr Doom took part in a contest of sorcerers (Marvel GN #49 Triumph And Torment). And indeed they are faced with a hissing Dr Doom who Blade denounces as a shapeshifter and Angela proves it by cutting him open. And she recognises its entrails as those of a Vridai, the Fae of the Asgardian realm Svartalfheim, who live in dark caves and can shapeshift but only into the form of someone they have captured (which means they must have Doom captive). She remembers a legend about them being woken by a broken bridge. Blade thinks they must have been woken this time by the destruction of the Black Bifrost by Freyja in War Of The Realms. (So how come 1 was active in Berlin years ago?)
As Angela and Blade have discussed this they've wandered into the temple without the others, and they get attacked by Vridai (not disguised as anybody). Assuming these are part of the gang that kidnapped and replaced them earlier Angela taunts them by asking how many of them it took to imitate *her*, before she and Blade gut most of them. The other 4 heroes then join in to deal with the rest.
Spectrum suggests they sneak further into the temple, but Angela just boldly marches in and calls out to their foes. They come into the presence of the leader Count Ophidian the Serpent Prince and his female aide/scribe(?) with a book (of spells?). After an exchange of insults Blade attacks with his sword but is repulsed by a magic barrier. Wiccan fires magic at the barrier while Spectrum and Bucky blast/shoot at it - all useless.
The aide summons the Royal Ritualist who turns out to be Daimon Hellstrom. Daimon is currently helping the Avengers in their own series and Blade assumes he's been captured and this is a shapeshifter. Whatever, Hellstorm counters Wiccan's attempt to alter the reality of the barrier (akin to his 'mother' Scarlet Witch's probability-warping hex power), and Spectrum's attempt to absorb the energy of the shield backfires on her. But the barrier collapses (and Ophidian, aide and throne seem to get disintegrated).
Blade takes the opportunity to kill the Ritualist, but he doesn't change into a Vridai. And Eric gets a phone call from Daimon's sister Satana to say that he's just showed up acting weird.