WARNING: This article contains major spoilers for Hunt For Wolverine: Adamantium Agenda #4 by Tom Taylor, R.B. Silva, Adriano Di Benedetto, Guru-eFX and VC's Joe Sabino, on sale now.
The X-Men have carried on without Wolverine, one of their most popular and recognizable figures, since the hero passed away in 2014's Death of Wolverine. While characters like X-23 and Old Man Logan have stepped up to fill the Wolverine void, it's fair to say the Marvel Universe has missed the X-Man and Avenger.
Of course, Wolverine wouldn't stay dead forever, and Marvel dropped the first bombshell in the hero's return story when he made a surprise appearance in last year's Marvel Legacy #1. Since then, a Hunt For Wolverine one-shot and four miniseries have continued the saga by revealing Logan's body to be missing to his friends in the superhero community. Each title took a different angle in the investigation, with Adamantium Agenda seeing the former New Avengers Iron Man, Spider-Man, Jessica Jones and Luke Cage coming together again to track Wolverine's stolen DNA.
With the help of X-23, the heroes' search uncovered the X-Men villain, Mister Sinister, as the mastermind behind a larger crime consisting of the theft of every person's DNA in the Marvel Universe. Looking back over Mister Sinister's history, this move aligns with his previous actions as a self-appointed expert in genetic manipulation. For example, Mister Sinister had a laser focus on Summers and Grey family trees when he first debuted, before settling in as a frequent X-Men threat.
This last point is important because while discovering Mister Sinister's surplus of DNA, Iron Man finds smaller databases for mutants and the X-Men. You would think having the DNA of every person on Earth would take top priority, but Mister Sinister only thought to have both a physical mutant DNA collection and a digital mutant database, clearly showing favoritism to those with the X-gene.
Tony almost let his scientific curiosity get the best of him, but his friends convinced him to destroy the databases instead of exploring the juicy information stored within -- but that doesn't mean Tony came out completely emptyhanded. Yes, Mister Sinister's DNA collection is no more, but Tony was able to decrypt two gene files ahead of their destruction.
The first file dealt with the identity of X-23's mother, which was revealed to be the scientist who gave birth to her cloned body, Sarah Kinney. However, the contents of the second file have a far greater impact on the X-Men and the Marvel Universe as a whole.