The Turin Shroud (the Sherlock Holmes Easter Special, Episode 2)

Having arrived in Turin, Sherlock Holmes and Dr Watson first checked into their accommodation and then immediately set off to speak with Cardinal Fassati. It transpired that only three people possessed a key to the Shroud Chapel: the Cardinal himself and two of his closest confidants, the elderly Pastor Spina and a younger pastor named Milani.
When Watson went out for an evening walk with his dog, he made a discovery in the park. 13 men had gathered around a table and were dining. One of them was wearing the Shroud of Turin. The case appeared to be solved, but additional duplicates of the missing shroud quickly surfaced. When a dead body was found in the chapel on Good Friday, the entire case took quite a different turn...