Harry and Tom, immortal soulmates-thanks to Harry being the Master of Death-decide to do a fun challenge. Tom ends up back in the 1940's, trying to convince a different Harry that, no, he's not out to murder all the muggleborns and make any horcruxes. Harry ends up in the summer after his sixth year and goes on a hunt for horcruxes with Ron and Hermione, while also making friends with a very familiar diary.