thereby hangs lies a tale

thereby hangs (or herein (or therein) lies) a tale

used to indicate that there is more to be said about something.
1948 Christopher Bush The Case of the Second Chance He and Manfrey were Brutus and Cassius respectively in that historic show at the Coliseum and thereby hangs a tale, or rather a piece of scandal.
1998 Spectator Now it has decided to fight back and clear its name. And herein lies a tale, however ludicrous.
See also: hang, lie, tale, thereby