Mr Holmes stars Ian McKellen as the great detective in his old age and while it could have proved a touching character study — who are you, not just when your mind starts to fail, but when the mind for which you are famed starts to fail? — it veers off in so many tedious directions that the end product is lumbering and leaden and will require 22 espressos thrown back in quick succession beforehand, along with several Red Bulls, if you are to have any hope of staying awake.