A teenage detective is shrunk back to childhood by a poison that should have killed him, and keeps solving cases under a fake name so the people who did it don't find him first. Running since 1996, case of the week with a long conspiracy underneath.
Notes so far: you can watch most cases in any order, but the organisation-focused episodes are easier to follow if you keep roughly to release order. A good show to put on without committing to a serial plot.