link in the chain
One of the steps, stages, or points in a development, process, or series of events. This new tram line is but one link in the chain of our greater plan to update the city's public transportation system. It was the deregulation of the market that proved to be the most crucial link in the chain of the eventual economic meltdown.
a link in the ˈchain
one of the stages in a process or a line of argument: Many people believe that coming from a broken home may be one of the first links in the chain that eventually leads to a life of crime.