Lady Penelope is a rather singular miss in that she wants nothing to do with a London Season, and nothing to do with marriage. Lucien Kenrick, Earl of Leighton, shares those same sentiments, so when the two are thrown together, there should be no problems, with neither of them in the least marriage-minded.
Then again, there's always that thing about best-laid plans... especially once both, through design and accident, end up residing under the roof of one Lucinda Benedict.