A throne of swans - Katharine Corr

When her father dies just before her birthday, seventeen-year-old Aderyn
inherits the role of Protector of Atratys, a dominion in a kingdom
where nobles are able to transform at will into the bird that represents
their family bloodline. Aderyn's ancestral bird is a swan. But she has
not transformed for years, not since witnessing the death of her mother -
ripped apart by hawks that have supposedly been extinct since the
long-ago War of the Raptors.
With the benevolent shelter of her
mother and her father now lost, Aderyn is at the mercy of her brutal
uncle, the King, and his royal court. Driven by revenge and love, she
must venture into the malevolent heart of the Citadel in order to seek
the truth about the attack that so nearly destroyed her, to fight for
the only home she has ever known and for the land she has vowed to
protect.Written in rich detail and evocative language, this is
the start of an irresistible, soaring duology about courage, broken
loyalties and fighting for your place in the world.

Katharine and Elizabeth Corr are sisters originally from Essex, now
living in Surrey. When they both decided to write novels - on account of
fictional people being much easier to deal with than real ones - it was
obvious they should do it together. They can sometimes be found in one
of their local coffee shops, arguing over which character to kill off
next. Katharine and Elizabeth are authors of the spell-binding trilogy The Witch's Kiss.

If you love Melinda Salisbury's royal politics and treacherous courts, you'll love this brilliant Game of Thrones-esque fantasy. There's no swearing (though there is a very tastefully vague sex scene, suitable for young teens) and only occasional (reasonably vivid) violence, but tons of intrigue, mystery, family drama, glamorous gowns and hidden swords.
Book Trust