If trying to crack the case gets you going why not try some of these books:
S1 - 3
Half-Moon Investigations - Eoin Colfer
Traces: Framed! - Malcolm Rose
The Body in the Library - Agatha Christie
Stormbreaker - Anthony Horowitz
Hound of the Baskervilles - Arthur Conan Doyle
S4 - 6
The Crow Road - Iain Banks
Deja Dead - Kathy Reichs
Knots and Crosses - Ian Rankin
Dead Famous - Ben Elton
Curious Incident of the Dog in the Nightime - Mark Haddon