Season 4

The actor and his son embark a 3,000-mile journey through Europe, aiming to experience extremes from the fiery heat of the Mediterranean to the icy tundras of the Arctic Circle. They begin in Croatia, where they swing off the roof of Hajduk Split's football stadium, before diving headfirst into the crystal-clear waters of the Adriatic. The action continues when the pair go head-to-head on aqua bikes alongside a former world champion, before heading to the capital Zagreb to meet a young inventor, who stuns them with his electric creation.

The actor and his son head to Hungary, where they take to the open waters of Lake Balaton for a spot of high-speed catamaran sailing with an Olympic crew, before warming up in their RV with some goulash. The pair finish in the capital Budapest, where Barney has arranged to meet a world-famous escapologist.

The pair continue their European adventure in Poland, going sightseeing in Krakow before attending an exclusive performance by the Polish National Radio Symphony Orchestra in honour of Poland's most famous composer Chopin.

The boys arrive in Denmark for the Scandinavian leg of their tour. Bradley's fear of heights is pushed to the limit with a visit to an offshore wind turbine.

The actor and his son head to Sweden, where they go head-to-head in a curling competition alongside the country's women's team in Stockholm. The next day, Barney treats his dad to an infamous fishy delicacy for breakfast, then takes him paintballing with a Western twist, and finally lines up a musical surprise for big Abba fan Bradley

In the final leg of Brad and Barney's epic journey, the pair experience a bitterly cold Norway. The boys head to Lillehammer and try out the Olympic bobsleigh track.