Song, Stone, Scale, Bone by Juliet Kemp

When Sir Cade, Knight of Siremos, is asked to escort a noble lady into the catacombs, she thinks she's getting a foolish thrill-seeker who will faint at the first sign of actual danger. Little does she realise that she is about to embark on a quest to save her country from being drawn into a war with a neighbouring kingdom.

Grieving the death of her companion Graf, Cade has lost her taste for rollicking adventure, but now she must grapple with ghosts, dragons, bone mages and political intrigue to heal her country and herself.

Take Me Home by E. M. Faulds

A tunnel is a hole, an absence, but also a conduit and a connection.

On one side of the world, Selen is looking for someone to be, and she thinks the spacetech alloy elagite may give her a way to rebel against her parents, impress her boyfriend and tap into her natural talents, whatever those might be. On the other side, in the Australian desert, her sister Phoebe has been drawn into an environmentalist cult: undercover, she finds it is far stranger and more dangerous than she could have expected. The girls' fates entwine in a way that could change things for everyone.