Riddle me this. How do you trap the untrappable? You get them to trap themselves. 
- — Batman
Detective Comics: Futures End #1 is a one-shot with a cover date of November, 2014. It was published on September 3, 2014.
Synopsis for "Anniversary"
The Calendar Man has been holding the staff of Arkham Asylum hostage for the last week, and now nearly three and a half hours remain on the deadline he set before he will pull the plug on Gotham City's power grid. His demands are merely for the man responsible for destroying his family. As far as Batman is concerned, that man is him - so he's on his way to forming an unlikely alliance with The Riddler.
The Riddler designed Arkham Island to keep its patients from escaping, but it's now so heavily fortified that the police can't penetrate its defences to rescue to the hostages. He breaks into the Riddler's building, fighting off Nygma's thugs, and confronts the man who put Gotham city into a forced blackout nearly ten years ago. Since then, though, he has received a full pardon - which Batman helped to orchestrate. When Nygma refuses to help, Batman reminds that if the Calendar Man triggers a blackout, it will steal the glory from the Riddler's Zero Year, and Nygma admits that this is enough to make him help.
En route, Riddler explains that he feels the Calendar Man is both very committed to his cause, and very crazy, which begs the question of why Batman thinks he can stop him. Batman explains that he was responsible for Julian Day's going over the edge. When his wife died, he gave up his job as a bouncer and became a hired thug for more pay. Despite having more money to support his son, he was a bad and abusive father. Batman put a stop to the abuse and put the boy in a home, leaving Day with nothing.
The pair swim down to a drainage pipe in the lower regions of the island, and begin working their way upward through the plumbing system, with Nygma posing riddles all the way, in the hopes of breaking the tension. Nygma leads them to a ladder, warning that there is a metal-detection based alarm system at the top. Batman can't remove some of the metal plates and pins inside his body, and so decides to simply go in anyway, regardless of the alarm.
At the top of the ladder, they emerge from a manhole in the courtyard, surrounded by Arkham Inmates. Together, the men fight off as many as they can, but are quickly overwhelmed. Intrigued by their partnership Calendar Man orders them to be released, prompting the Riddler to explain that he's come to deliver the man responsible for destroying Day's family. Calendar Man orders him taken away instead, explaining that his wife was killed during the blackout. His family ended the night his wife died. That makes the Riddler responsible.
As he is dragged away, the Riddler begs Batman to save him. Batman responds that their deal was only that he wouldn't turn Nygma over to the police. He has tricked the Riddler into trapping himself. With that, Batman leaves the Riddler to his fate.
Appearing in "Anniversary"
Featured Characters:
- Batman (Flashback and main story)
Supporting Characters:
- Alfred Pennyworth (Phone call only)
- Riddler
Antagonists:
- Calendar Man (Flashback and main story)
- Killer Croc (Cameo)
- Mad Hatter (Cameo)
- Man-Bat (Cameo)
- Mister Freeze (Cameo)
- Scarecrow (Cameo)
- White Rabbit (Cameo)
Other Characters:
- Aden Day (Flashback only)
- The Squid (Flashback only)
- Dick Grayson (Mentioned only)
- Gotham City Police Department (Mentioned only)
- Jason Todd (Mentioned only)
- Maggie Day (Mentioned only)
- Selina Kyle (Mentioned only)
Locations:
- Futures End
- Gotham City
- Arkham Asylum
- Riddler Tower
- Gotham City
Items:
Vehicles:
- Batboat
- Bat-Glider
Notes
- This issue is reprinted in Detective Comics: Anarky and Futures End: Five Years Later Omnibus.