Three Line Pitch - Tethered

Over the last few weeks I've been considering agent hunting. I've seen a few pitch contests on the internet but judged myself not yet ready and put them on my to-do list for next year. Yesterday, however, I saw the hashtag #pitchwars pop up on Twitter and decided to investigate. Pitch Wars is an "event where agented authors, industry interns, and editors team up with aspiring writers to shine up their manuscripts and pitches to present to some awesome agents." You can check out more details here. Aside from Keir's sequel I only have one MS complete that I can pitch - my sfr Tethered - and although I think this is probably too short for an agent, I decided it would do me good to at least throw my hat into the ring. So, I need a three line pitch. Below I have three drafts I've done, and I'd love your opinions on them. Seriously, let rip. I'd rather you were honest if they suck.

1.Every one hundred years the Terrans must renegotiate a peace treaty with the fearsome Tier-vane, or risk plunging humanity into a war it may not win. But when an assassination attempt succeeds in killing one of the two Terran delegates, Tyree of the Su - an assassin herself and sister clone to the murdered delegate - finds herself thrust into the role and in serious danger. Can she hide the fact that she's a replica and still prevent further attempts to wreck the treaty, while in danger of losing the heart she didn't know she had to her charming yet scarred co-delegate Zander D'joren?

2.Tyree of the Su is a psi-talented assassin, bred and trained, genetically perfect. But when her sister clone - one of a pair of delegates negotiating the essential peace treaty between the Terrans and the fearsome Tier-vane - is killed, Tyree must attempt to take her place. Her task - to keep herself and her co-delegate alive long enough to complete the negotiations without being spotted as a fake - and without losing her heart to her charming yet deeply scarred co-delegate, Zander D'joren.

3.When assassin Tyree of the Su is asked to take the place of her murdered sister clone as Terran co-delegate to the deadly Tier-vane, she's also assigned to protect the remaining diplomat - Zander D'joren. Her task - pretend to be co-delegate Mirsee in all ways, keep the pair of them alive long enough to complete the negotiations and return home to Refuge. But Tyree never expected losing her heart to her charming yet scarred partner to be as much of a risk as losing her life.