The Secret of the Elms

Twelve year old Mary Ellen has been expelled from St. Agatha's for smoking pot ― although she swears she was not ― and is subsequently whisked off by her half-sozzled father and vain stepmother to spend an extended Easter vacation at the Elms ― a gigantic Victorian-Gothic mansion belonging to her Grandmother. No mansion the size of a castle is complete without a screeching peacock, marble fireplaces, an ancient housekeeper, and a haunted nursery ― and the Elms comes fully stocked.

As they drop her off at the stone porte cochére big enough to contain a small house, Mary Ellen's parents also inform her that she will be joined by Grandmother's other two granddaughters ― a get together deliberately contrived in order to decide which deserving heir will be left the family fortune. No pressure there.
Although the three cousins are at first suspicious of each other, in no time at all they are deep in hair-raising (or shall we say, heir-raising?) mystery and adventure. Together they unravel the family secret, survive an enchanted snow storm, and even enter Hobbit in a gala horse show. Grandmother, by the way, hates horses, so when Mary Ellen falls in love with a miniature horse called Hobbit, she sneaks him into the nursery where he promptly chews on the Chippendale chairs and leaves other, more organic, remnants of his presence. (Won't that make grandmother happy.)
A great read for young adults full of ghosts and family secrets, coming of age, and friendships that empower the discovery of mutual strength, courage and self-acceptance.