015(stranger things story)

One night, a mysterious girl in her teens and a hospital gown shows up at the Hargrove house...claiming she knows them somehow. She had an old family photo clasped tightly in her scrawny right hand, she odd tattoo on the inside of her left wrist. the numbers tattoo'd were: 015. how will Billy react, finding out that THIS strange girl...is his sister. and his dad KNEW this whole time!
(Book 1 0f 2)