Episodes to look out for:

Riding for Mother Russia (Episode 105, April 6, 8.05pm). In embattled rebel-held eastern Ukraine, Michael embeds himself with The Night Wolves: a Kremlin-backed biker gang who have a direct line to Putin seeks their leader, “The Surgeon”, in Moscow.

Chasing Iranian Spies (Episode 102, April 13, 8.05pm. Once considered terrorists, backed by US politicians and led by a woman – this is the Mujahedeen-e-Khalq, an Iranian dissident group that Michael met during the war. Are they terrorists or freedom fighters? And where are they now?