This is an interesting magical-realistic story that I mostly enjoyed, but still has some issues regarding. 
 Setting: the book mainly takes place in a mythical land, the Lower Hundred, that was lost off the coast of Wales centuries ago. In my brain I liken it to Atlantis. It's a time-trapped land ruled by an Earl. 
 Sebastian Swift was the male heir to become earl. At age 13, he was wrongly accused of murdering his twin sister, August, and sentenced to an asylum where he's been abused the past 8 years. He's plagued by dreams of drowning, and one night a vicious storm tears his facility to shreds and he's rescued by the "ghost" of August. He's led to a conclave of cast-offs and thieves and taught how to survive on the streets. This is aided by Sven, a man who claims to be from the Upper Realms--and who makes ample use of Sebastian's, er, they have sex. A bit. Sebastian likes men, always has, and is happy to trade his body for protection. He won't reveal his true identity because he learns that an imposter has taken his place as Earl. Still their land languishes and the populace despises the Earl. Sven "hatches" a plan to masquerade Sebastian as August--returned from the "dead"--inorder to squeeze money from the Earl. 
 The changeling, Macsen, is the illegitimate offspring of Sebastian's elder cousin Emrys. He hated Sebastian and August, jealous of their easy life, and had no qualms assuming Sebastian's identity once Sebastian was convicted of murder. He doesn't believe August is who she claims to be, but he also doesn't believe she's Sebastian--at first. Once their true identities are made plain, Macsen and Sebastion must band together against Emrys--one would hope. To some degree they do, because there is a water shortage in the Lower Hundred that has been created by magic siphoned off Sebastian while he was a prisoner of the asylum. 
 Okay, this one was a real convoluted cloak-and-dagger read where Sebastian was a pawn in many games, Macsen was a pawn in some of them, characters come back from "the dead" and the ability to control water is not only important--it's vital. Emrys has plans to raise to alter their world in a way that would likely destry it--for his own monetary gain. He's a brutal man, and has no qualms about dispatching his enemies--or beating his son into submission. 
 I don't want to give too much away, but I'm not really sure that even writing out the major plot points would help it make sense in its entirety. I felt as disoriented as Sebastian, who is heartstrong and headstrong and looking for a place to be loved. Orphaned young, and abused long, he has no real sense of place, and he seems to find it with Macsen, despite their fraught history. Macsen redeems himself, mostly, for his youthful execution of his power-hungry father's orders and plans. He's a bit of a Robin Hood, at this point in time, stealing Sebastian's stolen magic to replace the water his father has stolen, if that makes sense...and helping "his" people from the horrific edicts laid out by Emrys, in the "Earl's" name. He does the right thing at the right time, even if he heart isn't completely in it. 
 I felt as it there were some moments of "convenience" that were too unrealistic--especially near the end. That said, I did connect with the love story between Macsen and Sebastian. The resolution was sweet as it stood, with an HEA that seemed plausible for the setting. All the bad guys get what's coming and Mac and Seb create a life that ensures their close quarters even as their open relationship would never be acceptable. I received a review copy of this book via NetGalley.