List<> Get Next element or get the first

I want to get the next element in a list and if the list is at it's end I want the first element. So I just want it to circle in other words.

   List<int> agents = taskdal.GetOfficeAgents(Branches.aarhusBranch);
    if (lastAgentIDAarhus != -1)
    {
        int index = agents.IndexOf(lastAgentIDAarhus);
        if (agents.Count > index + 1)
        {
            lastAgentIDAarhus = agents[index + 1];
        }
        else
        {
            lastAgentIDAarhus = agents[0];
        }
    }
    else
    {
        lastAgentIDAarhus = agents[0];
    }

I am fairly displeased with my own solution shown above, let me know if you have a better one :)