I am going to try and keep this Saga Campaign as thematic as possible, stemming from the ‘What If?’ of ‘What if Gandalf didn’t escape from Orthanc in The Fellowship of the Ring?’
When Gwaihir approached Isengard, bearing tidings for Gandalf and Saruman, he was fired upon by several orc archers. Warded off by the volume of arrows being loosed at him, he circled the valley out of bow-shot and what the Great Eagle saw dismayed him. Upon returning to Radagast and alerting him of what seemed as a captured Isengard, and hence an ensnared Saruman and Gandalf, Radagast alerted Cirdan, Elrond and Galadriel as the surviving members of the White Council. Hearing Gwaihir’s report of the industry in Isengard, with the valley now filled with orcs and wolves, as well as Saruman’s message to Radagast of the Nazgul having issued from their strongholds of Minas Morgul and Dol Goldur, the Council concluded that the Nine had captured Isengard and had either detained or slain the White and Grey Wizards. Galadriel consulted her mirror, in which she was shown a great host marching from Isengard, destroying all in its path.
With no more doubt in their minds, the Council sent scouts and messengers into the Shire, alerting every faithful friend of the danger now posed to Bilbo’s nephew. For Elrond knew of Bilbo’s ‘magic ring’, and that Frodo now possessed it, and when he learned of the Nazgul’s roving in the West coupled with Gandalf’s disappearance, he deduced only one thing would prompt The Dark Lord to move so boldly and openly: The One Ring. And as agents issued forth from Imladris, Lothlorien and Mithlond, Bilbo, filled with concern and regret at having unwittingly left Frodo in such great peril, sneaked away from Rivendell ahead of Elrond’s scouts to return to Bag End and help Frodo however he could. But he was not so foolish as to think he could go alone. Enlisting the help of his former companions Bofur and Dori, and Gloin’s son Gimli, he set off for the Shire.
Bilbo arrived in Bag End to find Frodo in the last stages of moving to Crickhollow, still awaiting Gandalf’s promised return. Merry and Fredegar had gone on ahead to Frodo’s new house, and Pippin and Sam were helping tidy away the last odds and ends. Joy at seeing Bilbo quickly turned to despair at hearing news of Gandalf, and so resolving to waste no further time, Frodo set off from Bag End, not fully comprehending the terrors of the road ahead.