Adonijah's sudden move to claim the throne triggers an immediate crisis in the royal palace. The prophet Nathan approaches Bathsheba with an urgent warning, making it clear that this is not merely a political struggle for power and prestige, but a true existential threat [מלבי״ם]. He offers her a plan to save both her own life and the life of her son, Solomon [ביאור שטיינזלץ]. The primary approach among commentators is that the main danger hanging over them is the threat of death. If Adonijah successfully establishes his rule, he will undoubtedly execute Bathsheba and Solomon as soon as King David passes away. Because Solomon was previously promised the throne, Adonijah would view him as a dangerous rival who must be eliminated to secure his own reign [מצודת דוד, רד״ק, ביאור שטיינזלץ].
Beyond the immediate danger of execution, the need for rescue is also understood as a way to prevent a bitter dispute and a bloody civil war. Since God promised the kingdom to Solomon, he would naturally demand his rightful place, making a military confrontation with Adonijah and his men inevitable [רש״י, צאינה וראינה]. An additional perspective suggests that the rescue is from severe disgrace and humiliation. Even if Adonijah chose to spare their lives, Bathsheba and Solomon would be forced to live out their days as his subjugated slaves [רד״ק, צאינה וראינה].
To prevent these disastrous outcomes, Nathan advises Bathsheba to go to King David's chambers immediately. She must remind the king of his oath to crown Solomon, acting right away rather than waiting until after David's death [אלשיך]. The origin of this oath dates back to the death of David and Bathsheba's first son. At that time, Bathsheba worried that the public would despise her future children because of the events surrounding Uriah. She refused to conceive again until David swore that her first surviving son would inherit the kingdom [צאינה וראינה].
Nathan carefully designs the strategy by sending Bathsheba to the king first. He does this out of fear for his own safety; if Adonijah's supporters discover that the prophet is the mastermind behind this counter-move, they will kill him [אלשיך]. The calculated plan ensures that Bathsheba enters first to present the case, and while she is still speaking with David, Nathan will enter the room to back up her claims and strengthen her position [צאינה וראינה].