Gideon, a top‑ranking trainee at Harthwick Conservatory, is supposed to obtain the highest‑rank spirit beast contract at the bonding dock. Instead he bonds with Rook, a so‑called zero‑value beast. His fiancée Cressida betrays him and conspires with patron Tobin to exile Gideon to the dangerous tidal pit. Gideon survives, forms a deep soul‑sharing bond with Rook, and defeats successive assassins sent by his enemies. He signs a death‑match waiver to compete in the academy’s open tournament to seek justice. During the contest, he uncovers behind‑the‑scenes murder plots, awakens royal‑blood power inside Rook, yet gets framed and captured. Helped by the fungus‑creature Pip, Gideon recovers his lost limb and life force. He returns to confront Cressida, Tobin and the corrupt academy head Oswald. Later he travels to the upper‑domain The Gilded Reach, discovers how the upper realm harvests mortal life‑force, and learns his long‑missing father Harlan is imprisoned there. After fierce battles against the upper‑domain ruler Oriana and the fused monster Briar Crown, Gideon sacrifices much of his lifespan. With collective power from academy members, both Gideon and Rook survive. Harlan is rescued. Gideon becomes the new dean, abolishes the old rank‑based spirit‑beast system, and ushers in a new era for the coastal land.
