Context : Nearby clusters of galaxies , z \lesssim 0.1 , are cosmic structures still under formation .
Understanding the thermodynamic properties of merging clusters can provide crucial information on how they grow in the local universe .

Aims : A detailed study of the intra-cluster medium ( ICM ) properties of un-relaxed systems is essential to understand the fate of in-falling structures and , more generally , the virialization process .

Methods : We analyzed a mosaic of XMM-Newton observations ( 240 ks ) of the Lyra system ( z \sim 0.067 ) that shows a complex dynamical state .

Results : We find the main cluster RXC J1825.3+3026 to be in a late merger phase , whereas its companion CIZA J1824.1+3029 is a relaxed cool-core cluster .
We estimate a mass ratio of \sim 1 : 2 for the pair .
No diffuse X-ray emission is found in the region between them , indicating that these clusters are in a pre-merger phase .
We found evidence of a galaxy group infalling on RXC J1825.3+3026 in an advanced state of disruption .
The SG , one of the brightest galaxies in the Lyra complex , was very likely at the center of the infalling group .
This galaxy has a gaseous ” corona ” indicating that it was able to retain some of its gas after the ram-pressure stripping of the intra-group medium .
In this scenario the diffuse emission excess observed southwest of RXC J1825.3+3026 could be due to gas once belonging to the group and/or to cluster ICM dislocated by the passage of the group .
Finally , we identified three high-velocity galaxies aligned between RXC J1825.3+3026 and the SG , two of these showing evidence of gas stripped from them during infall .
We estimate them to be currently falling onto the main cluster at an infall velocity of \sim 3000 km/s .

Conclusions : Our study of the Lyra complex provides important clues about the processes presiding over the virialization of massive clusters in the local Universe .