Free from the author via KDP Select @
Amazon:
The Powerhouse by "Ann Halam", YA pseudonym of multiple award-winning British sf/fantasy author Gwyneth Jones (
ISFDB,
Wikipedia), 4th in her Ghosts and Other Hauntings series of YA sfnal/supernatural adventure thrillers, this one a horror-ish haunted building installment originally out from Orion Children's Books in 1997.
Robs Hayward, a talented young pianist, is thrilled when she's recruited by Maddy Turner and Darryl (Jef) Jeffries, to join an experimental techno band. She's fourteen and a shy loner, Maddy and Jef are sixteen and super-cool. When their rehearsal space at school becomes a new car park, it's Robs who suggests they could use a mysterious, derelict old industrial building in the Wild Park. She doesn't tell them, she'd feel so stupid, that she's afraid it might be haunted. Everything works out okay, though The Powerhouse is being repurposed by the town Council, and they have to share it with a rather eccentric Artist in Residence . . .
Until Maddy, the bright flame, gets obsessed with an ancient murder mystery. Robs is certain that a seance would be a really, really bad idea. She doesn't think the thing she keeps seeing, out of the corner of her eye, is the sad ghost of a sweet hippie wild child. Maddy is determined to clear the name of an innocent man, but Robs has a horrible feeling there'll be hell to pay . . .