Used book – Fatal Drop, Fiona Kelly

The holidays get off to a bad start for Tracy, Holly, and Belinda. As soon as they arrive at Butterpike Hall, they witness a tragedy. A young boy falls into a frozen lake right before their eyes. And doesn't resurface! Despite the search efforts, his body remains undiscovered... First mystery. Shortly after this event, Mike, their instructor, completely changes his behavior. Why? Second mystery. If there's one thing the members of the Mystery Club can't stand, it's being faced with a mystery without trying to solve it. Except this time, there are two...