Retained search involves outsourcing the full process to a specialist recruiter who manages the complete process from candidate engagement through to offer. All you have to do is turn up and interview a short-list of pre-screened candidates.
On the surface, a retained search may look like a big cost and you may be put off by paying a portion of the fee up front. However, working this way frees your time up to focus on your job, increases the chances of success and costs no more than working on contingency basis.