Robert Plant concert review: At Wolf Trap, retro and fresh takes on Zeppelin's best

Robert Plant joked early in Monday's set that folks at Wolf Trap should be prepared for a night of "soft rock and REO Speedwagon covers." Nothing that followed was too soft, unless you count Plant's fairly laid-back 1983 solo single, "In the Mood," and there were no REO reprises. But Plant's amazing set was indeed loaded with plenty of covers, rendered in ways both retro and fresh, most of them being tunes made famous by the outfit Plant once sang for, Led Zeppelin.