A question about the Empire's attempts to retrieve the Death Star plans. Rogue One reinforces that the Empire will stop at nothing to prevent the plans falling into the hands of the Rebellion - they destroy the Citadel Tower on Scarif (killing many of their own forces) and Vader then kills a good number of Rebel soldiers in an attempt to prevent the plans from being handed over to the Tantive IV. At the beginning of ANH, more Rebels are killed in orbit over Tatooine, with at least one officer strangled by Vader. On the planet, Imperial forces destroy the sandcrawler and the moisture farm. Vader's instructions include: "...tear this ship apart until you've found those plans" and later "She must have hidden the plans in the escape pod. Send a detachment down to retrieve them. See to it personally, Commander. There'll be no one to stop us this time." Later, the stormtroopers have no hesitation in opening fire on the Falcon just before it leaves Mos Eisley and there are at least a couple of Star Destroyers in orbit. With all the Empire's ruthlessness in the immediate period before ANH, Imperial forces should be thoroughly combing Mos Eisley, checking every building, particularly as it's a backwater planet of no political significance. But the instant they're confronted with a locked door (where the droids are hiding), the stormtroopers basically shrug their shoulders and move on to the next building. Why is that?