The End of Eternity (1955)

Andrew Harlan helps an organisation alter history to reduce human suffering, working at a distance from the lives affected. Personal attachment makes that professional detachment increasingly difficult. Asimov offers a compact causal puzzle with an unusually useful ethical pressure: who decides which risks other people should be allowed to take? Technical competence, institutional confidence and desire pull in different directions; leave room for the narrative to revise your understanding of the system.