In Defiance of Gravity is a thrilling piece of theatre for many reasons. It’s a fabulous story. It’s brilliantly acted. And watching it, late evening, in the perfectly atmospheric, perfectly apposite Demonstration Room at Summerhall, is a spookily thrilling experience.

Writer and director Saul Boyer tells us a tale of the (supposed) greatest spirit medium of all time, Ezra Montefiore. A committed opium addict, he’s hopeless at managing his money so when a long lost friend – who happens to be a Prince in Russia in the years leading up to the Russian Revolution – turns up, he’s eager to help his friend contact his dead brother. Prince Felix Yusupov (Lewis Chandler) is a fascinating character in his own right.

The story whips along, tautly directed by Toby Hampton who embraces all possible opportunities for spookiness without neglecting the story’s emotional truth. Superb performances from all actors make the fantastical seem like a solid reality. Boyer’s a hypnotic medium, a fevered opium lover and charismatic enough that the unfolding antics seem perfectly reasonable. Chandler is all louche, debonair charm – part privileged playboy, part little boy lost. Laurel Marks has possibly the trickiest job as she flips in a heartbeat between Yusopov’s wife, Irina’s icy restraint and Montefiore’s earthy, opportunistic spiritualist pimp. The contrast between the two is hugely entertaining.

For reasons that alone are worthy of the ticket price, Montefiore, Yusupov and Irina end up embroiled in a plot to murder Rasputin. You’ll know the Boney M song. You possibly know that they tried both poisoning and then shooting Rasputin but he appeared to emerge unscathed from both. But here is the backstory: entirely fantastical but the brilliance of Boyer’s script is you’ll come to see that it was the only conceivable course of action for those involved.