Here is a brief outline I have for the plot. The time is approximate and free to change. What are your thoughts/ideas?

Spearhead
Outline

I.
President of the Federation is assassinated by a member of the military in the Federation. An elaborate plan to frame the Empire is put in place, to invade their home world. Days later at the Academy, Captain Daniels is giving a speech at graduation when an explosion goes off, targeting key military members in attendance. (20 minutes)

II.
The departure of the ENDEAVOR, the lead military vessel, begins the invasion. The Endeavor led fleet encounters heavy resistance from the Empire. During an intense battle, the Federation support vessels jump away from the fight, leaving the Endeavor alone, fighting an Empire Armada. The Endeavor surrenders, and the Empire take Captain Daniels, and his staff prisoners aboard their ships. (30 minutes)

III.
On-board the Empire ship, the Empire Captain tries to convince Captain Daniels that the Empire has nothing to due with the assassination, and that it was an inside job. The Empire has a spy on the inside with vital intel in regards to the assassination that is shown to Captain Daniels, who is hesitant to believe it. To show their innocence, the Empire lets the Endeavor leave with Captain Daniels. The Endeavor heads toward the Empire home world alone. (15 minutes)

IV.
On their way to the Empire home world, the Endeavor encounters another race that they have never seen before. They attack the Endeavor, using weapons that have been documented in the Albitro Wars by an unnamed race. This new race, is superior in technology and offers to help the Endeavor reach the Empire home world faster than their current pace. Captain Daniels and 3 members of his crew (Science Officer, Tactical Officer and Chief Engineer) board the alien ship, and head to the home world. (15 minutes)

V.
The alien ships arrives at the home world, just before a Federation armada. The alien ship goes cloaked, as the Federation arrives. The Federation opens talks to the home world to discuss surrender, and the alien ship monitors the conversation. During the talks, the Chief of World Military on board, confirms the information of treason. Captain Daniels demands that the new aliens confront the Federation, however they do not. The Federation attacks the Empire home world, however the Empire has re-enforcements and destroy the Federation ships. Distraught, the alien ship takes Captain Daniels and his staff back to the Endeavor. (20 minutes)

VI.
As Captain Daniels and his staff arrive back on the Endeavor, they head back to Earth. Captain Daniels ignores orders from Earth command to head to the Empire home world. Command threatens to meet Captain Daniels with force if he returns to Earth. A close friend to Captain Daniels is called to lead an armada against a hostile vessel headed to earth, though he does not know who it is at the time. As the Endeavor arrives, Captain Daniels informs his friend of the information he has learned, but he doesn't believe him. Captain Daniels refuses to surrender, and before a fight begins, the Alien ship uncloaks. Unab;e to sway his friends mind, Captain Daniels and the Endeavor engage in a firefight with the Earth Armada. The Alien ship makes quick work of some of the support vessels, ultimately leading to the surrender of the Earth Armada. (25 minutes)

VII.
Captain Daniels takes his friend on-board the Endeavor, shows him the information, and together, they both go to Earth Command to confront acting Chief of Earth Military. Unable to take him peacefully, a firefight ensues, taking the life of the acting Chief, and seriously wounding Captain Daniels friend. Security surrounds Captain Daniels and he gives up. During court-martial, Captain Daniels manages to convince everyone with the evidence he has of the treason, and the Federation and Empire call a cease fire. The Alien ship appears in orbit after the trial, damaged, requesting assistance. Once Captain Daniels and a boarding party arrive on board, they discover that many of the crew is dead, and a video message is left, telling them to go to their home world. (20 minutes)

Total: 145 minutes.