There's one obvious problem with your call(): it uses "who" as the session name so the call goes nowhere. The first argument must be the name of your IRC session. You can directly call handlers on the IRC session object but that doesn't seem the right way of using it. Synchronous calls should only be used when you can immediately obtain a result, which in this case you can't anyway because it has to handle IRC protocol stuff first which is itself asynchronous.

Try $irc->yield(who => $where); with the example code in the SYNOPSIS, as the last thing in _start. The result should be returned in some message---which one will be visible in the output from the _default handler.