A lanky young woman from the 25th century wakes up more than 800 years later and discovers that she is only an electronic copy of a deceased person in an almost immortal composite body of a personal cybernetic android, stuck on a colony with a medieval level of development that survived an interstellar genocide; that this level is set by an artificially created creationist religion, implanted into the brains of colonists washed during cryosleep, and is forcibly supported by the dominant omnipotent Church, suppressing attempts at a scientific approach; that going beyond strictly prescribed technologies may be punished by an orbital threshold system of kinetic meteorite bombardment, already tested in the destruction of the minority who do not agree with the oblivion of all past history; that it still has at its disposal a few modern production facilities and weapons, local transport and communications facilities with controlled autonomous orbital and atmospheric surveillance facilities, a decent electronic library and a dull but promising computer intelligence; and, most importantly, it represents the last hope for the rebirth of humanity. She takes on this incredibly difficult task, having previously assumed the male appearance of seijin Merlin on a patriarchal planet, beginning to act gradually, like a beneficial virus, first infecting one cell of the body, and for this purpose she chooses the peripheral island kingdom of Charis, moving towards the industrial revolution, with active trade, offering his services to the ruling dynasty and winning their trust by saving the life of the crown prince. She manages to introduce into circulation deliberately forgotten Arabic numerals, a positional system for recording numbers and abacus abacus, revolutionize the textile industry, shipbuilding and metallurgy of the kingdom with enormous benefits for trade with other countries, improve firearms, achieve the start of the construction of military galleons with powerful artillery to replace the existing ones galleys and train part of the navy and marines in new tactics, before the worried, corrupt elite of the Church decides to destroy the overly rich and suspiciously innovative kingdom at the hands of the five other sea powers obedient to it. In three decisive battles at sea, the renewed fleet of the kingdom sweeps away the fleets of the aggressors, but this is only the beginning, because the Church is not going to lose its power and its influence - there are bloody religious wars and a struggle for the minds of the inhabitants of the planet Safehold ahead.