From publisher blurb:
Few adventurers enjoy the reputation given to a paladin, the armored knights famed for their oaths of service to the divine and rigid codes of conduct. Naturally, though, with fame also comes pretenders who would try and take advantage of that reputation for their personal gain. Rogues who emulate the Mountebank archetype are deceivers who would simply dress the part of the crusading paladin, enjoying the fame (or infamy) which comes from these real holy warriors' deeds.
Building off of the existing Fifth Edition rules to build a rogue character, the Mountebank gives you options to build a deceptive rogue willing to disguise themselves as a traveling paladin and take advantage of the goodwill these holy warriors experience.