House of Black.

Bianca and Nellie Tonks finished the 4th year of Hogwarts, last year was an insane year for them but it just gets worse, they both need to hide with the Order because voldemort is after there doupleganger power. Dumbledore's army begins and Bianca is a secret spy for them tracking umbrage every move. Bianca still morning the death of her friend and Nellie going through relationship struggles. This is going to be one rough year.

Friendships, Lovers and Enemy's all in the mix.

[This is the second book of the series! Go read Twins before this one!]