This story takes place after decommissioning, when Hoagie, Abby, Kuki and Wally are all teenagers, and Nigel still hasn't returned. But he does. And they all don't remember him. Why did Nigel return? And life always seems to put old friends back together…

An Adventure takes place a year after the events of Sonic Chronicles: The Dark Brotherhood. Sonic has been travelling for the last year, and a lot has happened. Knuckles has disappeared, and someone has come looking for him. With Tails and Amy, Sonic embarks on a journey that will explore his roots and the species he belongs to, and face his biggest challenge yet.