8) Why Did Eurus Destroy Baker Street?
Later on in the episode, Sherlock, John and Mycroft are in Baker Street when a drone flies through the window. It’s carrying a “patience grenade” that will detonate once one of them moves. As such, their best shot at survival is to jump towards the stairs and out the window when it explodes.
We could ask just where the Holmes’ boys evil sister Eurus got the grenade from, but the more pertinent question is why she’s trying to kill them? We later find out that Eurus has been playing a very long game that’s been leading to her testing her brothers and John with a series of cruel experiments in the Sherrinford facility. Why, then, would she risk all that planning being for aught when she almost kills them here? There was no way she could know that they would survive it, right?
Speaking of which, how do all three of them make it out alive without nary a scratch on them? We can presume that some time has passed by the following scenes but it can’t be have been that long.