Keep me 'till the petals fall (and even then, hold me close)

The Rose Robberies have been stumping the best of Scotland Yard for two years. Now they've put Harry Potter on the case. He's not the best (or so they think,). The ink on his diploma is still wet. But he did pretty well in analysis, maybe he'll spot something they didn't. or In which Harry Potter is a detective, a criminal, and a mastermind in no particular order.