The series centers on the fictional British government agency MI: 13, which is dedicated to protecting the United Kingdom from supernatural threats.

The main strikeforce is led by the superhero Captain Britain (Brian Braddock), and consists of various Marvel Comics characters that are of British descent or have a connection to the country.

To help keep the series on schedule after the completion of the first story arc, Pat Olliffe and Paul Neary took over the art duties for issue #5 (the prologue to second storyline Hell Comes to Birmingham) from Leonard Kirk and inker Jesse Delperdang.

The initial main cast of characters included superheroes with British backgrounds like Captain Britain, The Black Knight, and Spitfire working for MI: 13 alongside its field agents Pete Wisdom and John the Skrull.

[19] In issue #3, readers saw the return of Merlin, a version of the Merlyn usually seen in stories with Captain Britain (who is the physical amalgamations of all his interdimensional counterparts), specifically an 'aspect' that appeared in Marvel UK's Doctor Who comics.

[20] This fits with the mention of "Higher Evolutionaries" having imprisoned him, a group who appeared in Alan Moore's "Time War" storyline and who have Rassilon as a member.

Cornell has a strong Dr Who connection and explained his choice of this 'aspect' of Merlyn: I think we just all liked the look of Merlin with a metal skullcap, as seen in the film Excalibur.

[25] The evil released by Wisdom in "Guns of Avalon" starts to cause trouble, chiefly thanks to Plokta, a new character: He's a lovely new Leonard design, in a rather Steve Ditko vein.

Dracula, "the greatest general of his generation",[19] and his vampire minions leave their Moon sanctuary for a planned assault on the United Kingdom; with help from Doctor Doom.

Cornell has said that it would be "a spy game, a clash of intellects, as Dracula tries to strategize and trick his way into a full on takeover of the British Isles".

The team members are each intercepted by enhanced vampires, while Dracula heads directly to Faiza Hussain's family home.

Kidnapping and converting Faiza's father and others while seemingly using his powers over Spitfire to bring her into his inner circle, that includes Lilith and Captain Fate where Dracula uses magic to prepare for an invasion.

Brian launches a second attack to assist her, this time showing his full power against Lilith, just in time for Dracula to learn that Wisdom had not led him to the skull of Quincy Harker but had instead led him to a fake; every action by MI:13 was to ensure Dracula wouldn't know the protection spell around the country was still active, leading to the vampire army being mostly wiped out as they remain uninvited.

Dracula and his remaining loyal soldiers retreat to their fortress, trying to protect Lilith, but are pursued by MI:13, MI:13's reserves, and a Special Air Service team.

In the aftermath, Faiza has achieved knight status, Dane Whitman's stone heart curse has worn off, and the two of them (along with Brian & Meggan and Spitfire & Blade) have officially paired up.

Members of MI-13 attend an official reception in America, presided over by Steve Rogers, given in their honor for being the first country in the world to get rid of the Skrulls.

Reactions from the MI-13 team are mixed, but Wisdom eventually, reluctantly declares that Brian will accept, and they can work out some sort of time-share.

[28] While the other core members of MI-13 attend an official reception in America, Spitfire and Blade (on MI-13 orders) hunt for someone in New York[29][30] Reviews of the first issue were largely positive, noting Cornell's solid characterization and tight plotting[31] as well as the vein of black comedy that runs through proceedings[32] and the smooth transition from his Wisdom limited series, despite the differences in the scale of the action,[33] which may make the issue "a little new reader unfriendly.

[46] When talking about the close of the title, Cornell stated "Our audience really left at issue four... People protest about events, but try and write a comic now without them.