"The Mysterious Four" by Dan Poblocki is a nail biting series that Mubasshira and Sylvia from room 20 have done an excellent review on. Take a listen!
Three friends Sylvester, Rosie and Woodrow live in the neighbourhood of Moon Hallow. When a new girl named Viola arrives in to the neighbourhood the three friends welcome her into their group only to find out she solves mysteries as a hobbie.
The group took a liking to Viola's hobbie and decided to form their own crew named the 'Mysterious Four'. Moon Hallow became a neighbourhood full of mysterious lurking around every corner waiting to be solved by the Mysterious Four.
Check out this awesome podcast these girls have created for this very intriguing book!