The most stunning relic in Hamilton and Carl's collection - the black obsidian chalice - is examined. The pair then head to Portugal to hunt for clues about the chalice.

Carl Cookson and Hamilton White investigate a Crusader sword and helmet that date back more than 900 years. Oxford historian Dr Janina Ramirez helps them decode the symbolism on these ancient relics to show that the sword may have been used in the First Crusade when Christian knights retook the holy city of Jerusalem, and that the helmet, embossed with the Lion of St Mark, was made in Venice. Travelling to Italy’s ‘floating city’, Carl and Hamilton learn more about how and why Venice adopted St Mark as its patron saint and went on to become a leading maritime power – eventually supplying crucial ships for the Crusades. They also discover that, on the way to Jerusalem, the Venetians chose to attack the Christian city of Constantinople to recoup losses they had sustained in building the fleet. In the archives Janina discovers a powerful and vivid first-hand account of the “Sack of Constantinople” by a government official who was living in the city at the time.

Treasure hunter Hamilton White and friend Carl Cookson have an amazing hoard of relics - believed to have belonged to the Knights Templar. Can they prove their provenance?

Carl and Hamilton investigate an extraordinary collection of Celtic gold from the Iberian Peninsula that dates back thousands of years. Amongst the rare artefacts are a gold bowl worth over £1m, fine pieces of jewellery depicting the goddess Astarte, and a stone altar to the god Endovelicus which might have been used in rituals that involved blood sacrifice. Travelling to Portugal, where most of the Celtic gold is from, Carl and Hamilton meet up with Joao, their long-time local guide and collaborator. The three men travel to the site of a very rare temple devoted to Endovelicus and explore how the temple might have been used to worship the god. Carl and Hamilton meet up with forensic archaeologist and former police detective Roger Box. They want to find out more about the Roman symbolism that appears on the Celtic altar, and Roger takes them to the site of a Roman temple in the Cotswolds.

Hamilton has amassed an extraordinary collection of Nazi memorabilia. These include a collection of Nazi badges that were sold to raise money for the German poor, and an ammunition box full of silver bullion bars that were found buried close to a concentration camp in Poland. The badges incorporate many symbols from other ancient religions and cultures that the Nazis used to promote the myth of an Aryan master race. The Nazi relics have a deeply personal resonance for Janina as she is Polish, and her grandmother was interned in a Nazi labour camp during the war. Janina begins her part of the investigation into the Nazi obsession with religious symbolism by looking into Nazi Grail hunter Otto Rahn, the inspiration behind the Indiana Jones movies. She discovers documents that reveal Rahn, who eventually committed suicide, was gay and had Jewish ancestry. Carl and Hamilton begin their investigation at a stunning mountain-top monastery at Monserrat in Spain.

Exquisitely shaped from marble, the libation vessel is Carl's favourite piece in the hoard. Could its four carved heads be depictions of John The Baptist?