We've known for some time now that Aiden Pearce from the first Watch Dogs, and Wrench from Watch Dogs 2 were going to feature together in the Bloodline DLC, but the latest trailer seems to imply they'll actually be enemies, rather than fighting for the same side - at least at first.
Aiden is heading to London, where his nephew, Jackson, has apparently moved in the intervening years, under instructions from Jordi Chin, another favourite character who featured in both Watch Dogs and Watch Dogs 2. When he arrives in England's capital, he finds Jackson has been abducted, and he'll need to steal a futuristic piece of tech to get him back, of course.
As for why Wrench is in London, that is less clear, but what's obvious is he and Aiden don't get along when they bump into each other. After a face-off, Wrench takes the gadget and fleas, meaning you'll likely have to track him down to get it back.
The new DLC is launching on July 6th, and will be included as part of the Watch Dogs Legion season pass.