The 23rd installment of the long-running Precure series. 
 
Anna Akechi is a second-year junior high student living in Makoto Mirai Town. On her 14th birthday, she has a chance encounter with a fairy named Pochitan, and a magical pendant caused her to travel back in time from 2027 to 1999! In the Makoto Mirai Town 28 years in the past, Anna meets Mikuru Kobayashi, a girl her age who wants to become a great detective. 
 
Meanwhile, people in town are in trouble as their prized possessions are being stolen from under their noses - the cause being a group of Phantom Thieves. To stop them, Anna and Mikuru turn into Precures! Maybe if they solve these mysteries, Anna can find her way back to her own time? 
 
(Source: Official Website, translated)