Probing Wales' most mysterious mysteries, from aliens to ghost animals, the Unexplainers are here to prove the truth is out there. A big cat is on the loose in north Wales and John's convinced that it's up to him and his skeptical companion Mike to track it down.When a complicated mix of CCTV, woodwork and cold meat yields some unexpected results the hunt for a rogue Puma spirals into a much bigger career in professional monster hunting. Armed with some new kit, the Unexplainers set sail on a lake near Bala to search for a reported lake monster. But when things don't work out on the surface, John is desperate to go deeper and Mike becomes convinced that this monster business could generate him some monster business.