Redirect to flow.. completely, listener, execution, security, example

amy

I have a security flow execution listener which on sessionStarted does some checking.Code:
public void sessionStarting(RequestContext context, Flow flow, AttributeMap input) {
// checking if(breech){  // forward to new flow }
}
Where a security breech has been deteched, how can I redirect the flow to a completely new flow, for example to a login screen?