The hook about this is a man seeing his own murderer so I think perhaps best to start with that as an inciting incident. The first sentence in this logline feels redundant because the “…I see the future…, …I see dead people…, …I see murders…” super natural element is well established as a trope in film and TV. Also the exact nature of the mechanism by which the man sees the future is unrelated to the plot at hand of him stopping the killer.

Here is my try:
After a clairvoyant is given a vision of his own murder he has a week to find and stop the killer.

Better to add in some character descriptions for the antagonist and MC but none are in the current draft of the logline and as the above example is very lean there is plenty of room to add words.

Hope this helps.

No need to name the MC in a logline unless it is critical for the reader to understand the story.

This reads like an interesting fantasy concept with similarities to the Narnia, Alice in Wonderland or The Endless Summer books with the gateway into the new magical world being the attic window instead of a cupboard, rabbit hole or book.

The challenge in my mind facing most magical gate way stories is not the originality of the gate way as the mechanism by which the MC enters the magic world is less important than the story on the other side. Rather it is connecting the “normal” world with the “magical” world or reflecting the problems the MC has in the “real” world through the problems he or she have in the magical world.

In this logline there seams to be little cause and effect relationship between the missing father, dead girl and the magical land. Perhaps if you re word the logline to read that the reason the MC entered the magical world was to follow the footsteps of his missing father. Also it feels as if the stakes would be higher if the father would go searching for a little boy as the father could presumably fend for him self better than a little boy can. This way you can increase the potential for danger and maybe even introduce a ticking time bomb such as; “…must find the boy before a ferocious monster gets him…”.

e.g:
After his son disappears an accountant discovers his footsteps leading into an attic window he follows and falls through the window into a magical land where he meets a dead girl that can help him find his son before a ferocious monster finds him.

Or something to that effect.

Hope this helps.